REVIEW OF OPHIDIOID FISH GENUS OLIGOPUS — COHEN 9 



lateral canal and ventrally by scaleless area that demarcates separate 

 patch of scales posterior to rear margin of maxillary. 



Lateralis system: Lateral canal with 1 pore near upper angle of 

 opercle. Supraorbital canal with 2 pores: 1 in front of anterior 

 nostril; the other, very small, above anterior nostril. Infraorbital 

 canal with 5 or 6 pores: 3 in row behind anterior nostril; 1, very 

 small, near level of posterior margin of eye (absent in USNM 193678) ; 

 and 2 above posterior expanded portion of maxillary. Preoperculo- 

 mandibular canal with 8 pores: 2 at tip of dentary, 1 opening 

 anteriorly, the other posteriorly; 1 beneath lower lip close to level 

 of posterior nostril; 1 slightly ahead of level of posterior margin of 

 maxillary; 1 near lower angle of same; 2 shaped like elongate slits, on 

 posterior margin of preopercle. 



Cu'cumorbital and interorbital areas and side of snout cavernous 

 and covered with thick skin bearing many small, dark, dermal papillae 

 similar to those marking course of lateral lines along side of body. 

 These filaments particularly abundant in interorbital region. 



One series of lateral line filaments numbering about 35-45 and 

 originating on head above opercle and, after slight irregular dip 

 near origin, extending posteriorly in straight line between midline of 

 dorsal profile, this dorsal line terminating more than half way back 

 along body. Second line of about 35-40 filaments originating at 

 about midhne close to level of posterior tip of pectoral fin, descending, 

 then rising to midline of body to form irregular semicircle having 

 lowest point opposite origin of anal fin, then extending in straight 

 line in midline of body to tail. 



Dentition: Premaxillary bearing uniform band of granular teeth. 

 Dentaries bearing similar teeth plus irregular row of larger, conical 

 teeth along inner edge of granular band. Head of vomer with widely 

 spread wings bearing short granular teeth. All four specimens 

 females. 



Head spines: Short, weak spine present at upper corner of opercle. 

 May be buried beneath skin and invisible without dissection, or barely 

 visible at its tip. Posteroventral margin of preopercle may be com- 

 pletely rounded or show 2 slight angles. Maxillary spine varying from 

 prominent projection pictured in holotype to virtually absent condi- 

 tion in 1 Liberian paratype. 



Vertebrae and ribs: Neural spines 5-13 short and broad but becoming 

 progressively more elongate and narrower, their tips more or less (5 

 and 13) truncate; neural spines on subsequent centra needle-like. 

 Centra 7-12 with ribs at ends of parapophyses, subsequent centra 

 lacking pleural ribs. Centra 4-9 with epipleurals attached to pleural 

 ribs; on centra 10-13 epipleurals appearing to be associated with 

 parapophyses. 



724-329—64 2 



