1915.] NATURAL SCIENCES OF PHILADELPHIA. 229 



Pygidium poeyanum (Cope). 



Trichomycterus poeyanus Cope, Proc. Amer. Philos. Soc, XVII, 1877, p. 47 



(on T. rivulatus Cope). 

 Trichomycterus rivulatus (non Valenciennes) Cope, Proc. Acad. Nat. Sci. 



Phila., 1874, p. 132. Arequipa, Peru. 



Nos. 21,382 and 83, A. N. S. P., cotypes of T. -poeyanus Cope. 

 Arequipa, Peru. J. Orton. This species is close to P. rivulatum, 

 differing in its large, dark blotches. 



Pygidium dispar Tschudi. 



One example, which Cope refers to as "a large specimen of the 

 T. yardus, which, according to the label, came from Callao Bay." 

 At present, however, it is labelled as having been secured at Tinta. 

 Pareiodon microps Kner. 



Amazon between mouth of Rio Negro to Peru. 



CALLIOHTHYID^. 



Calliohthys callichthys (Linnaeus). 



Surinam, Nauta, Pebas, Ambyiacu River and Rio Jacuhy. This 

 large series shows considerable variation. Adults and young have 

 variably long or short pectoral spines, which may reach the ventral 

 or only half as far. Plates on caudal base in two clusters, which 

 may vary 3 or 4, though usually 4 in each. 

 Hoplosternum littorale (Hancock). 



Trinidad and Venezuela. 



Hoplosternum thoracatum (Valenciennes). 



Nauta, Ecuador. 



Hoplosternum oronocoi sp- nov. Fig. 8. 



Hoplosternum tJwracatum (non Valenciennes) Fowler, Proc. Acad. Nat. 

 Sci. Phila., 1911, p. 436. La Pedrita, Venezuela. 



Head 3f; depth 3|; D. I, 7; A. i, 5; P. I, 8; V. i, 5; lateral 

 plates 25 above, 23 below, to caudal base; snout 2y'^ in head; eye 7; 

 mouth width 3^; interorbital If; dorsal spine 2; adipose spine 3|; 

 pectoral spine If; anal spine 2|; least depth of caudal peduncle 

 If; caudal 1; ventral If. 



. Body moderately long, well compressed, deepest at dorsal origin, 

 and edges all convex. Caudal peduncle greatly compressed, as 

 measured to last anal ray, base about half as long as deep. 



Head moderate, depressed, upper profile little more inclined, 

 surfaces all convex. Snout broad, depressed, and length about 

 f its greatest width. Eye small, rounded, laterally superior, hind 

 edge about midway in length of head. Mouth moderate, upper 

 jaw very slightly protruding. Teeth minute, in broad bands in 



