Nicaragua is thus divided into three longitudinal zones. The most easterly is covered by a great unbroken forest; the principal products being india-rubber and mahogany. The central zone is composed of grassed savannahs, on which are bred cattle, mules, and horses. It is essentially a pasturage country, though much maize and a little sugar and indigo are grown in some parts. The western zone skirts the Pacific, and is a country of fertile soil, where all the cultivated plants and fruits of the tropics thrive abundantly; the rich, fat land might, indeed, with a little labour, be turned into a Garden of Eden.

In the autumn of 1871, it became necessary for me to proceed to Granada to empower a lawyer there to act for us in a lawsuit in which we were engaged. Taking Velasquez and a servant with me, I rode over to Juigalpa on the Ist of November. We had intended to go by land to Granada, but we learnt that, through continued wet weather, much of the low land of the delta of the Malacatoya was impassable, so we determined to make for the lake, and try to get a boat to take us to Los Cocos, from which place there was a good road to Granada. We found at Juigalpa a Libertad storekeeper, named Señor Trinidad Ocon. He had already engaged a boat, and courteously offered, if we could not find one. when we got to the lake, to give us a passage in his.

We started from Juigalpa the next morning; and for the first few miles our road lay down by the river, a deep branch of which we crossed. The alluvial plains bordering the river were covered with fine, though short, grass, amongst which were some beautiful flowers. The orange and black "sisitoté" (Icterus pectoralis, Wagl.) flew in

EMBARK TO CROSS THE LAKE.

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Ch. XVIII.] small flocks amongst the bushes; and the "sanaté" (Quiscalus) was busy amongst the cattle. Their usual plan of operations is for a pair of them to accompany one of the cattle, one on each side, watching for grasshoppers and other insects that are frightened up by the browsing animal. They keep near the head, and fly after the insects that break cover, but neither encroaches on the hunting ground of the other.

We stopped at a little hacienda perched at the top of a small hill. It was called "El Candelera," and was a small cattle station, surrounded by plains. We then crossed the valley, and made for a range of hills between us and the lake. The ascent was steep and rocky; and it took us two hours to get to the top. We then saw the great lake, like a sea lying spread out before us, but still at a considerable distance. The descent was very steep, and we had to make long detours to avoid precipitous ravines. At last we reached level ground; but it was even worse than the mountain roads to travel, being in many parts wet and swampy. After missing our way, and having to retrace our steps for more than a mile, we reached Santa Claro, a cattle hacienda, at dusk. Here we found Señor Ocon's boat, but there was no other. The boatmen said we must embark at once. We made an arrangement with a man who had accompanied Ocon to take our mules to San Ubaldo, as we proposed to return that way. The boat was small, and there were seven of us; so that with our saddles and luggage we were much cramped for room.

They poled the boat for two miles down a small river that emptied into the lake, but just before we reached it, the boatmen stopped and said it was too rough to proceed

that night, and notwithstanding our remonstrances they tied the boat to some bushes. Our cramped position was very irksome; the river was bordered by swamps, so that we could not land, and thousands of mosquitoes came about and rendered sleep impossible. About midnight, the moon rose, and two hours later we prevailed on the boatmen to set sail, but, notwithstanding their excuse about it being too rough, there was so little wind that we made slow progress. At eight we went on shore, where there was a hut built close by the lake below Masaya. The lake was flooded, and the water had been over the floor of the hut during the night. All around were swamps, and the mosquitoes were intolerable. We could buy no food at the miserable shanty, and soon set sail again. A little more wind afterwards springing up, we reached Los Cocos at eleven o'clock. a small village at this place, where we got breakfast cooked, and did justice to it. We hired horses to take us to Granada; but as the road for a league further on was overflown by the lake, we went on in the boat, and a boy took the horses round to meet us, swimming them across the worst places.

There is

Glad we were to get on horseback again, and to canter along a hard sandy road, instead of sitting cramped up in a little boat, with the sun's rays pouring down on us. The path led amongst the bushes, and was sometimes overflowed, but the soil was sandy, and there was no mud. All the beach was submerged, or we should have ridden along it. The last time I had passed by this part of the lake was in July 1868. Then the waters of the lake were low, and we rode along the sandy beach, black in some parts with titanic iron sand. The beach re

Ch. XVIII.]

FRESH-WATER ANIMALS.

331

sembled that of a sea-coast, with the waves rolling in upon it, and to the south-east the water extended to the horizon. Along the shore were strewn shells thrown up by the surf; and on examining them, I found them all to belong to well-known old-world genera-Unio, Planorbis, Ancylus, and Ampullari.

On this journey, all the beach was, as I have said, covered with water, and I saw no shells; but in the pools on the road were water-beetles swimming about, and these showed a surprising resemblance to the waterbeetles of Europe. Gyrinida swam round and round in mazy circles; Dytiscido came up to the surface for a moment, and dived down again to the depths below with a globule of air glistening like a diamond. Amongst the. vegetation at the bottom and sides of the pools Hydrophilide crawled about, just as in ponds in England. Not only were those familiars there, but they were represented by species belonging to the typical genera

-Gyrinus, Colymbetes, and Hydrophilus. Over these pools flew dragon-flies, whose larval stages are passed in the water, closely resembling others all over the world. All the land fauna was strikingly different from that of other regions; but the water fauna was as strikingly similar.

The sameness of fresh-water productions all over the globe is not confined to animal life, but extends to plants also. Alph. de Candolle has remarked that in large groups of plants which have many terrestrial and only a few aquatic species the latter have a far wider distribution than the former. It is well known to botanists that many fresh-water and marsh plants have an immense range over continents, extending even to the most

remote islands.*

The close affinities of fresh-water animals and plants have been noticed by many naturalists. Darwin saw with surprise, in Brazil, the similarity of the fresh-water insects, shells, &c., and the dissimilarity of the surrounding terrestrial beings compared with those of Britain.+ Dr. D. Sharp informs me that water-beetles undoubtedly present the same types all over the world. He believes there is no family of Coleoptera in which tropical or extra-tropical species so closely resemble one another as in the Dytiscido. Cybister is found in Europe, Asia, Africa, Australia, New Zealand, Brazil, and North America ; and the species have a very wide range. Dr. Sharp remarks that this wide distribution and great similarity of the Dytiscido is of special interest when we recollect that they are nothing but Carabidæ fitted for swimming, and yet that the Carabidae are one of the groups in which the tropical members differ widely from the temperate ones.

For following up this branch of inquiry the study of the distribution of the mollusca offers special advantages. There are numerous marine, fresh-water, and terrestrial species and genera. They are slow moving; they have not the means of transporting themselves great distances, like insects, for example, that may easily and often pass over arms of the sea, or fly from one country to another. Their shells are the commonest of fossils; and in islands such as Madeira and St. Helena, where we have abundant remains of extinct land shells, there are few, if any, of extinct animals of other classes or of plants.

Taking the shells of Europe, we find a remarkable * Darwin, "Origin of Species," p. 417. + Ibid., p. 414.