7. PTERIDITJM. 375 



Operculum with a spine posteriorly. Cheeks scaly. The dorsal 

 commences above the middle of the pectoral. Yellowish-green ; a 

 violet cross-band behind the eyes. 

 Batoe, Nias, Goram. 



a. Young. From Dr. P. v. Bleeker's Collection. 



2. Dinematichthys maxginatus. 



Brosmius marginatus, Ayres, I. c. i. p. 13. 

 Halias marginatus, Ayres, I. c. ii. p. 52. 



The height of the body is equal to the length of the head, and 

 two-ninths of the total. Upper jaw overlapping the lower ; palatine 

 bones with teeth anteriorly only. Operculum terminating in a short, 

 sharp spine. Head naked ; snout longer than the eye, its length 

 being nearly equal to the width of the interorbital space. Fins en- 

 veloped in a thick membrane ; the dorsal arises over about the middle 

 of the pectorals. Brown. 



San Francisco. 



6. BYTHITES. 



Bythites, Reinh. in Dansk. Vidensk. Selsk. Afhandl. vii. 1838, p. 178. 



Body elongate, covered with minute scales ; lateral line interrupted. 

 Eye of moderate size. Vertical fins united ; ventral reduced to a 

 single simple filament*, inserted at the humeral symphysis. Bands 

 of teeth in the jaws, on the vomer and the palatine bones. Jaws of 

 equal length. Barbel none. Eight branchiostegals ; gill-membranes 

 united, not attached to the isthmus ; air-bladder large, rounded pos- 

 teriorly. Two pyloric appendages. A thick, conical, horizontal 

 papiUa behind the vent (in the male). 



Greenland. 



1. Bythites foscns. 



Reinhardt, I. c. p. 179. tab. 7 & 8. 

 The height of the body is less than the length of the head, which 

 is nearly one-fourth of the total ; head large, thick, with the snout 

 obtuse ; cleft of the mouth wide, the maxillary extending behind the 

 eye. Head with minute cirri. Vertical fins enveloped in thick skin ; 

 ventrals two-thirds as long as the head. Uniform dark-brown. 



Known frorii a single specimen more than 3 inches long, and fully 

 described by Prof. Reinhardt. 



7. PTEEIDIUM. 



Oligopus, Risso, Ichth. Nice, p. 141 (not Lacep.). 

 Pteriaiimi, Scopoli. 



Body elongate, covered with rather small scales; lateral line 

 double along a portion of the tail. Eye of moderate size. Vertical 

 fins united ; each ventral reduced to a single short filament, composed 



* It is formed by two rays, which are united by a common membrane. 



