236 LOWER VEliTEBRArES. 



form, and the nostrils single ; the dorsal is armed with numerous spines, and the anal 

 is also often possessed of many spines, never with less than three. The species are 

 numerous, and naturally confined to the fresh waters of tropical and sub-tropical 

 America and Africa, although the species of two genera have broken their African 

 bonds, and extended and developed in the neighboring portion of Asia. 



The Ciclilida3 are interesting on account of their range of variation, their various 

 peculiarities of structure, and their habits. Probably all take care of their young, 

 and some have a very peculiar way of doing so. The male parent takes the newly 

 laid eggs in his mouth, and there they mature and hatch. Species of three genera, two 

 African {Tikqna and Hemichromis) and one AmcriKOii {Geophagus), exercise this 

 peculiar mode of incubation or oral gestation. 



Africa is the headquarters of the genus Tilapia, (formerly called f7tro»i/s), that has 

 been considered to be the type of the family Chromidida? or Cichlidae, but the genus 

 has become extended into contiguous portions of Asia and is represented by not 

 less than seven species in Palestine. The species have an oblong body and in aspect 

 considerably resemble a sunfish ; the teeth are in several rows, compressed and lobate, 

 and much larger in the outermost row; the dorsal fin has fourteen to eighteen spines, 

 the anal only three. The celebrated bolti of the Nile ( T. iiilotica) belongs to the 

 genus and is also found in Palestine, in Lake Tiberias, and in this same lake is 

 found another species ( T. simonis) dedicated to the apostle Simon or Peter. If we 

 must get hold of that fish out of whose mouth the apostle got the tribute-money, 

 (and the task has often been attempted) this is as good a one to identify with it as any. 

 If it lacks a spot behind the shoulders, many species of the family have one. At any 

 rate, the species is peculiar to the Jordan system, and, as far as known, is restricted 

 to lakes Tiberias and Huleh. 



Dr. Lortet has given us some interesting observations on the propagation of T. 

 simonis, which are worthy of being ti'an scribed. 



" The spawn is of the size of No. 4 shot, of a rich deep green. The female de- 

 posits about two hundred eggs in a little excavation which she works out among the 

 rushes and roots. When she has completed hei- labor, she appears exhausted, and 

 remains motionless at a little distance. The male, on the contrary, appears much 

 agitated, turns himself about the spawn, swimming constantly above them, and pro- 

 bably fecundates them at this moment. In a few minutes afterwards he takes the ova 

 one after another into his mouth, and keeps them in the buccal cavity against his 

 cheeks, which then appear swollen in an extraordinary manner. Some of them, how- 

 ever, escape through his gills. The ova, though they are not attached by any mem- 

 brane, nor by any glutinous matter whatever, remain very securely in his mouth, and 

 are never dropped while he is in the water. It is only when he is thrown out on the 

 sand that, in the struggle of his death-agony, they fall out, many however, remaining 

 even then in his mouth. 



"lu this novel hatching-oven, the eggs, during several days, undergo all their met- 

 amorphoses. The little ones rapidly increase in size, and appear to be much incom- 

 moded in their narrow^ prison. They remain in great numbers, pressed one against 

 another, like the grains of a ripe pomegranate. The mouth of the father-nurse now 

 becomes so distended by his progeny, that his jaws cannot meet. The cheeks are 

 swollen, and the animal presents the strangest appearance. Some of the young, 

 arrived at their perfect state, continue to live and develop among the folds of the 

 branehiip. Others have their heads turned towards the mouth of the parent, and do 



