132 ZOOLOGY OF THE VOYAGE OF THE BEAGLE. 



the adipose, or perhaps a trifle beyond it; two small spines at its commencement; the first two 

 soft rays simple, the others branched. Caudal forked for half its length, the lobes equal ; the whole 

 fin contained about six and a half times in the entire length ; the accessory rays very numerous, 

 and partially fringing the upper and lower edges of the tail. Pectorals attached behind the 

 gill-opening, rather below the middle, about two-thirds the length of the head, of a somewhat 

 triangular form, the rays gradually shortening from the first, which is the only one unbranched. 

 Ventrals attached a very little in advance of the dorsal, rounded, or almost cut square at the 

 ends, the rays being all nearly equal. They are scarcely shorter than the pectorals : the space 

 between their insertion and the commencement of the anal is nearly double their own length. 

 There is no long scale or appendage of any kind in their axillas. 

 Colour. — " Dull leaden colour." — D. — In spirits it appears brown. The sides are banded with 

 some irregular transverse zebra-like marks, not noticed by Mr. Darwin, reaching from the 

 back down two-thirds or three- fourths of the depth, some terminating sooner than others. All 

 the fins brownish. 



Habitat, Falkland Islands. 



Mr. Darwin obtained three specimens of this remarkable fish all precisely 

 similar, from a fresh-water lake in the Falkland Islands, in March. The lake 

 was not far from the sea, and connected with it by a brook. He adds in his notes 

 that the species is common there; that it is good eating, and grows to be about 

 half as large again as the individuals procured. 



One of these specimens was dissected by Mr. Yarrell and myself, and pre- 

 sented the following internal characters, which are of importance to be noted. 

 The coats of the stomach were thick and muscular ; the oesophageal portion with 

 prominent longitudinal plicae. Its contents, so far as they could be ascertained, 

 consisted of the remains of caddis-worms. The intestine was large, without any 

 coecal appendages, but with one spiral convolution at the end of the first third of 

 its length from the pyloric orifice : the entire length of the canal was four inches. 

 The air-bladder was large, undivided, and of the same general form as in many 

 of the Salmonida;. There were two elongated flattened lobes of roe nearly ready 

 for exclusion. The anal and sexual orifices were separated, but enclosed in a 

 tubular sheath, common to both, directed backwards ; the sheath itself lying in a 

 groove in the abdomen, and five-eighths of an inch in length : the opening to the 

 cavity of the abdomen and sexual organs was at the extreme end of this sheath, 

 and partly closed by two lateral valves ; the opening to the intestine, three-eighths 

 of an inch short of the extremity. 



2. Aplochiton t^niatus. Jen. 

 Plate XXIV. Fig. 2. 

 A . olivaceus, punctis fuscis minutissimis irroratus ; later ibus vittd longitudinali ar- 

 gented : maxilla inferior e longiore. 



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