REPORT ON THE DEEP-SEA FISHES. 



161 



Pseudorhomhus, Blkr. 



Dr. Hector has kindly sent to me the specimen from 400 fathoms which was given 

 him by Sir Wyville Thomson for description, and which served as a type of his Pseudo- 

 rhombus hoops. On comparing it with the second specimen from 150 fathoms, brought 

 home by the expedition as a "co-type" of that species, and consequently described by 

 me under the same name in Shore Fishes, p. 26, I find considerable difi'erences in the 

 proportions of various parts of the head ; differences which are quite in accordance with 

 the depths at which the two specimens were found, and which are sufficiently developed 

 to call for specific distinction. I give here comparative descriptions and figures of the 

 heads of both specimens, from which it will be seen how far the development of bathybial 

 characters has proceeded in the specimen from the greater depth. 



Pseudorhomhus hectoris. 



Pseudorhomhus hoops, Giinth., Report on the Shore Fishes, Zool. Chall. Exp., pt. vi. p. 26 (not 

 Hector). 



D. 117. A. 89. P. 12. L. lat. 78. 



The dorsal fin commences above the nostrils. The height of the body is two-fifths of 

 the total length (without caudal), the length of the head nearly one-fourth. Scales 

 ciliated ; those on the head and on the anterior part of the body smaller than those on 



FlQ. 4. — Head of Pseudorhombus hectoris. 



FiQ. 5. — Head of Pseudorhombus 



the tail. Interorbital ridge very narrow and naked. No spines or tubercles along 

 the lateral line or the base of the fins. The curve of the lateral line is strong, but flat 

 above. Snout rather shorter than the eye, the diameter of which is two-sevenths of the 

 length of the head. Lower jaw scarcely prominent when the mouth is shut. The 



