286 PROCEEiDINGS OF THE NATIONAL MU9E.UM vol.94 



6a. Anterior fourth or more of upper surface of snout naked and with 

 barbels at least in males well developed; in females snout bonier 

 and barbels sometimes absent; interoperele and opercle separately 

 movable, former with graduated evertible spines with tips hooked; 

 belly naked; teeth with elongate bilobed tips; dorsal a little in front 

 of peh ics; about 23 to 26 plates in lower lateral series. 



Ancistrus Kner 



6b. Anterior dorsal surface of snout bony, except on a few species with 



tip of snout having a roundish naked patch not much larger, 



sometimes smaller than orbit. 



7a. Teeth usually 3-3 on premaxillaries and 6 to 12 + 6 to 12 on den- 



taries, tips elongate but not spoon-shaped; interoperele with a 



bunch of spines with curved tips; dorsal I, 7; anal I, 3 to I, 5; 



pectoral I, 5 or I, 6; lateral scutes about 24 to 26. 



Lithoxus Eigermann 

 7b. Teeth in ramus of each jaw number 5 to 16, expanded tips spoon- 

 shaped or cupped, with or without a smaller lobe; dorsal rays 

 always I, 7; anal I, 4; no barbels on tip of snout. 

 8a. Interoperele and opercle separately movable, former with 

 graduated, elongate, evertible spines, except in young; about 

 6 to 8 cup-shaped teeth on ramus of each jaw ; belly covered 

 with platelets, except on young; dorsal origin nearly over 

 insertion of pelvics; 24 to 26 plates in lower lateral series. 



Panaque Ligenrnann and Eigenmann 

 86. Interoperele and opercle slightly but not independently mov- 

 able; sphies on interoperele absent or obpolete; dorsal origin 

 a little in front of a verticle line through insertion of pelvics; 

 25 to 28 plates in lower lateral series; color of upper surfaces 

 usually consisting of numerous dark spots, these sometimes 



occurring on belly Cochliolon^e Meckel 



7c. Teeth in each ramus of jaws number more than 20, usually 25 to 



65, and expanded tips are elongate and bilobed; dorsal origin 



in front of that of pelvics. 



9a. Interoperele and opercle separately movable, former v.i{h a 



rosette of graduated spines with hooked tips and long slender 



bristles arranged around outer margin of sjnnes; dorsal I, 7; 



anal I, 5; plates in lower lateral series 24 or 25; belly 



naked Lasiancistrus Regan 



95. Spines and bristles on interoperculum, if present, not arranged 



in pattern of a rosette; belly with ] latelets except in young. 



10a. Interoperele and opercle separately but moderately movable, 



former with short or elongate avertible spines; plates 



along lower sides 26 to 28 in number. 



Henaiancistrus Bleeker 

 10&. Interoperele and opercle slightly but not independently 

 movable; interoperele without spines, or spines obsolete; 

 plates along lower sides about 28 in number. 



Hypostomus LacepSde 



" On the young up to a standard length of about 50 mm. the unworn teeth of my specimens from the 

 Maracaibo Basin have their expanded tips twice as Ion? as wide and a sinall lobe on the outer side, but in 

 those about GO mm. the lobe seems to have fu^ed with the rest ol the tooth as it wears down to half its original 

 length; the teeth on the lower jaw lack the second small lobe at a nmch shorter length, it appears, therefore, 

 from the specimens available, that one must cast serious doubt on the validity of the genus Cueiridodiu 

 Eigemnann. 



