MR. F. DAY ON THE HEBEIDAL ARGENTINE. 79 



Length of head 4|, of caudal fin 7|, height of body 6£ in the 

 total length. Eyes with moderately wide adipose lids, the ante- 

 rior of which rather overlaps the posterior above the centre of the 

 upper edge of the orbit ; diameter of eye 3^ in the length of the 

 head, 1 diameter from the end of the snout and also apart. The 

 shape of the fish is as follows : — The back, sides, and abdominal 

 surfaces flattened, so as to give it a general tetragonal form, these 

 various surfaces being divided one from the other by a well- 

 developed ridge. These four flat surfaces are further subdivided 

 by other parallel ridges, one of which is a short distance internal 

 to the upper orbito-caudal ridge ; a second a little above the 

 pectoro-caudal ridge. In addition to these four secondary ridges, 

 there exists another short one from the lower edge of the base of 

 the pectoral fin to the ventral. Snout conical and somewhat de- 

 pressed; upper surface of the head flat, its sides compressed. 

 Upper jaw slightly longer than the lower; the maxilla scarcely 

 reaches above two thirds of the distance to beneath the front edge 

 of the eye. The suborbital ring of bones, the prseopercle, opercle, 

 and upper portion of the subopercle with a rather thick adipose 

 covering. Teeth : none in the jaws ; an arched row of small ones 

 across the head of the vomer, and continued on to the anterior 

 and contiguous portion of the palatines ; a single row of eight 

 large and somewhat recurved ones are placed on the upper sur- 

 face of the front portion of the tongue. Gill-rakers rather 

 widely separated, thick, and the longest about one fourth the dia- 

 meter of the orbit in length. Fins — First dorsal as high ante- 

 riorly as the body beneath it, its posterior rays about two fifths the 

 height of its front ones ; adipose fin placed above the last anal 

 rays ; pectoral if turned forward reaches the middle of the eye ; 

 ventral inserted in the middle of the distance between the end of 

 the snout and the base of the caudal fin, while it is beneath the 

 last dorsal ray ; anal highest anteriorly, where it equals the length 

 of the base of the fin ; caudal forked. Scales large, thin, higher 

 than long ; those along the back adherent, those on the sides more 

 deciduous. Minute ossicles, having a stellate or spinate form, 

 exist on the scales of the back, and also on some of those in the 

 abdominal region. The row of scales immediately beneath that of 

 the lateral line is the largest ; most ha\>e somewhat crenulated 

 edges. Lateral line on a row of smaller scales, well marked, and 

 passing to the centre of the base of the caudal fin. C cecal appen* 

 daqes— five long ones, loaded with fat. The example is a male, full 

 of milt. Colours — of a light olive along the back, becoming silvery 



