276 PROCEEDINGS OF THE ACADEMY OF 



not yet been described, two specimens in Mr. Hubbard's collection, the 

 possession of an authenticated specimen, received by the Institution, from 

 M. Agassiz enabling me to do so with perfect certainty. 



Hyperprosopon anal is has been truly affirmed by A. Agassiz to have "the 

 general appearance and about the size of Metrogaster aggregatus Agass., but 

 the teeth and the shape of the dorsal fin show that it is a true Hyperprosopon, " 

 and, notwithstanding the superficial resemblance to another type, it may be 

 added, that the physiognomy is also essentially more like that of Hyperpro- 

 sopon than Cymatogaster (or Metrogaster Ag.) The difference between it and 

 the typical species of Hyperprosopon is, however, so great as to authorize its 

 generic separation. 



The body is oblong, the height little exceeding three-tenths of the extreme 

 length, of which latter the head forms less than a fourth. The head itself 

 is oblong conic ; the diameter of the eye about equal to a quarter of its length, 

 and not much longer than the snout ; the latter is as high or higher than the 

 upper border of the pupil ; the forehead less depressed than in H. argenteus. 



6 



D. IX. 22. A. III. 24. Scales 65 . 



16 + 2 

 The color is silvery, slightly tinged with brassy on the sides and light pur- 

 plish on the back ; the margin of the elevated spinous portion of the dorsal 

 is blackish, and the anal has a very distinct ink-like spot between its fourth 

 and eleventh rays. 

 The species referred to Hyperprosopon may be thus distinguished : 



I. Body convex and high, the height more than a third of the 



length, and the back behind nape convex. Head rhom- 

 bic, about as high as long. Eyes very large. Snout short. 



D. IX. 2627. A. III. 3234 Hyperprosopon. 



a.. Ventrals with a broad terminal black band. 

 8 



Scales 85 H. argenteus. 



20-21 

 8 



Scales 72 H. arcuatus. 



21 

 8. Ventrals uniformly colorless H. agassizii.* 



II. Body oblong, subfusiform, with the back before the dorsal 



scarcely convex. Head oblong-conic. Eyes moderate. 



D. IX. 22. A. III. 24 Hypocriticktkys. 



6 



Scales 65 H. analis. 



16 



* Hyperprosopon agassizii' Gill. 



This species is closely related to H. arcuatus Gibbons, but the occipital region is 

 more elevated and obliquely convex; the caudal fin less emarginated, its margin dark 

 and the ventral fins are colorless. 



8 



D IX 27. A. III. 33. P. 25. Scales 65 . 



1920 

 This species is the one to which the name of H. arcuatum Gibbons refers in the 

 " Notes on the described Holconoti," by A. Agassiz. Gibbons' species is, however, 

 quite different, and rather allied to H. argenteus than to the present one. 

 The following table shows the relative proportion of the several species: 



arg. arc. Ag. 



Extreme length (=100) 7* 8* 61 



Height, 36 36 37 



Head Length of head, 24 23 _ 23 



Eye Diameter, 7c 74 7 



Snout Length 5 5 5 



[June. 



