942 CONTRIBUTIONS TO NORTH AMERICAN ICHTHYOLOGY — IV. 



than long-; the bony bridge across the occiput but little shorter than the 

 ])art of the head which precedes it. In A. y-grcecum the naked area i^s 

 trapezoidal, longer than broad, and about 4 times the length of the snout: 

 the Y is forked for more than half its length, its undivided part more 

 than twice as long as broad, and not concave; the occipital plate is not 

 half as long as the part of the head which precedes it. 



Page 629. After Astroscopus anoplus add : 



Family GUI (5) — OPISTHOGNATHID^. 



Body oblong or elongate, low, moderately compressed, covered with 

 small, cycloid scales. Lateral line present, usually incomplete, straight, 

 running close to the dorsal fin. Head large, naked, the anterior profile^ 

 decurved. Mouth terminal, horizontal, its cleft utiually verj^ wide, the 

 maxillary extending past the eye, and sometimes considerably beyond 

 the head; supplemental maxillary present; premaxillaries protractile; 

 jaws snbequal, with conical or cardiform teeth ; vomer usually with a 

 few teeth; palatines toothless; opercles unarmed; no suborbital stay. 

 PseudobranchioB present. Gill-rakers rather long; gills 4, a slit behind 

 the fourth; gill-membranes united, free from the isthmus. Branchios- 

 tegals 6. Air-bladder present. No pyloric coeca. Dorsal fin long, con- 

 tinuous, its anterior half composed of slender, flexible spines; caudal 

 distinct, rounded or lanceolate; tail diphycercal; anal long, without 

 distinct spines; ventrals separate, jugular, I, 5, the middle rays long- 

 est; pectorals fan-shaped. Two genera, of about 12 species, inhab- 

 iting rocky bottoms in tropical seas. Their relationships are apparently 

 with Trachinoid forms, but they bear considerable resemblance to the 

 Clinoid Blennies. {Trachinidce, genus OpistJwgnathiis Giinther, ii, 254- 

 256.) 



a. Maxillary of moderate length, truncate behind Gnathypops, 338 (b). 



aa Maxillary of great length, prolonged in a flexible lamina behind. 



Opisthognathus. 338 («;)• 



33S (&).— Gi\ATHYPOPS Gill. 



(Gill, Proc. Ac. Nat. Sci. Phila. 1862, 241: typo Opisthognathus maxillosusFoey.) 



This genus includes those Opisthognathidce in which the maxillary is 

 of medium length and truncate behind. {yvdOo<;, jsiw; u-w, below; a)^, 

 eye. 



977 (b). G. maxillosilS (Poey) Gill. 



Color grayish olive, with 7 irregular ^shaped bars of darker, every- 

 where much marbled and variegated; fins all similarly marked, the 



