354 CALIFORNIA ACADEMY OF SCIENCES. 



A. Adipose fin absent. Hisonotus lxxvii. 



hh. Adipose fin present. Parotocincltjs lxxviii. 



gg. Temi^oral plate perforated, coarsely sieve-like; no adipose fin; 

 dorsal inserted over origin of ventrals. Otocinclus lxxix. 



ee. Ventral surface naked or covered with minute, granular plates; in- 

 testines greatly elongate, many times as long as the body. 



Plecostomin^:. 

 I. Temporal plate perforate; dorsal inserted far behind the ventrals. 



MiCROLEPIDOGASTKR LXXX. 



a. Temporal plate imperforate. 

 j. Margin of the snout granular or sometimes a naked spot at tip; 

 scutes of the lower surface of the tail exposed. 

 k. Dorsal I, 7 or 8. 



I. Teeth fine, scarcely enlarged at tip, usually numerous. 

 m. Interopercle without erectile spines. D. I, 7. 



n. Adipose fin present. 



o. A. 6; tail comparatively long, terete; adipose fin far 

 removed from the dorsal fin; ventral surface with a 

 median, subcircular patch of granules; (species of 

 small size). Neoplecostomus lxxxi. 



00. A. 5; tail short, compressed; distance of adipose fin 

 from dorsal not much longer than base of dorsal fin, 

 sometimes much shorter; ventral surface irregularly 

 granular. (Species of moderate and large size.) 



Plecostomus lxxxii. 

 nn. Adipose fin none. Khinelepis lxxxiii 



mm. Interopercle with erectile spines, borne on a movable 

 plate. 



p. Dorsal and adipose fins distant. 



Hemiancistrus lxxxiv. 

 pj:). Dorsal and adipose fins subcontinuous. 



Parancistru.'^ lxxxv. 



II. Teeth enlarged, bowl-shaped at tip, few, overlapping; adi- 

 pose fin present. D. I, 7; A. 5. 



q. Interopercle Mdthout erectile spines. 



COCHLIODON LXXXVI. 



qq. Interopercle with a large bundle of erectile spines. 



Panaque lxxxvii. 

 kh. Dorsal I, 10-13. Pterygoplichthys lxxxviii. 



jj. Margin of the snout with spines or bristles, not granular, 

 r. Adipose fin present. 

 s. Lower surface of the tail rounded, the plates exposed; dor- 

 sal short, the last ray not adnate. Not more than one 

 azygous plate in front of the adipose spine; marginal spines 

 of the head longest on the preopercle. 



Pseudancistrus lxxxix. 



