THE SHORE FISHES OF PERU 489 



possessed by S. sechurae. In two specimens of the two species, each 

 about 65 mm. long, the head is contained 2.3 times in the length, and 

 the interorbital 13 times in the head or 5.9 times in the snout in 

 angusticeps, whereas the head is contained 2.6 times in the length, 

 and the interorbital 6.4 times in the head or 3.3 times in the snout in 

 sechurae. 



Range. — Gulf of California to northern Peru. No specimens from 

 the Galapagos Islands or Panama Bay were seen. 



Family GOBIESOCIDAE: Clingfishes 



Body rather long, anteriorly broad and depressed; premaxillaries 

 protractile; mouth moderate or rather small; teeth usually strong, the 

 anterior ones conical or incisorlike; opercle reduced to a spinelike 

 process, more or less concealed in the skin, and sometimes obsolete; 

 gills 2}^ or 3; gill membranes broadly united, free or united with the 

 isthmus; scales wanting; dorsal and anal similar, at least partly 

 opposite each other, consisting of soft rays only; ventral fins far 

 apart, each with a concealed spine and four or five soft rays; a large 

 sucking disk on chest, the ventrals forming a part of it. 



The generic classification and the identification of the specimens, 

 with the omission of trinomials, used in the preparation of the descrip- 

 tions were furnished by L. P. Schultz, who studied the Peruvian 

 material in the preparation of his recent paper on the American 

 clingfishes (Schultz, 1944). 



Three genera were recognized among the Peruvian specimens studied. 



KEY TO THE GENERA 



a. Each jaw anteriorly with incisors, either with smooth or indented cutting 

 edges; dorsal and anal small; each with about 5 to 10 rays (visible without 

 dissection) . 

 b. Incisors in part at least with 2 indentations, the middle pair often 

 with smooth edges; opercular spine small, not projecting beyond mem- 

 branous margin above it; origin of anal Uttle behind that of dorsal. 



Arbaciosa (p. 489) 



bb. Incisors all with entire, and nearly straight cutting edges; opercular spine 



very large, projecting well beyond membranous margin above it; origin 



of anal behind middle of dorsal Sicyases (p. 491) 



aa. Lower jaw anteriorly with somewhat compressed teeth with entire rounded 

 or somewhat pointed cutting edges; teeth in upper jaw scarcely compressed, 

 pointed, in 2 irregular series; dorsal and anal larger, the former with 11 to 

 15 and the latter with 10 to 13 rays (visible without dissection); origin of 

 anal under anterior third of dorsal Sicyogaster (p. 493) 



Genus ARBACIOSA Jordan and Evermann, 1896 



Snout with a strongly convex anterior margin formed by the pre- 

 maxillaries and lip; premaxillary groove slightly concave medianly; 

 each jaw anteriorly with large incisors, the middle ones often with 



