1915.] NATURAL SCIENCES OF PHILADELPHIA. 235 



Lithoxus lithoides Eigenmann. 



Mem. Carnegie Mus., V, 1912, p. 242, PL 29, figs. 1-4. (Warraputa) British 

 . Guiana. 



No. 39,121, A. N. S. P., paratype. Warraputa, British Guiana. 



In exchange Avith Carnegie Museum. 



HYPOPTOPOMIN^. 

 Hypoptopoma thoracatum Gunther. 



Hypoptopoma bilobatum Cope, Proc. Amer. Philos. Soc. Phila., XI, 1870, 

 p. 566, 2 figs. Pebas, Ecuador. 



Nos. 8,280 and 81, A. N. S. P., cotypes of H. bilobatum Cope. 

 Pebas, Ecuador. J. Hauxwell. These agree with H. thoracatum 

 in their ventral armature. In the smaller example the median series 

 of scutes do not approximate those on each side. 



Also an example from the Peruvian Amazon. 



Hypoptopoma psilogaster sp. nov. Fig. 9. 



Hypoptopoma bilobatum (part) Cope, Proc. Amer. Philos. Soc. Phila., XVII 

 1878, p. 679. Peruvian Amazon. 



Head 4; depth 6|; D..I, 7; A. I, 5; P. I, 6; V. I, 5; 26 plates 

 in lateral series, of which last on caudal base; 3 predorsal plates; 

 head width If in its length; head depth at occiput 2; snout If; 

 eye 4f; mouth width 3|; interorbital If; least depth of caudal 

 peduncle 3|; pectoral spine li. 



Body long, slender in lateral profile, depressed as viewed from 

 above, deepest at dorsal origin, and edges all smoothly convex. 

 Caudal peduncle rather robust, becoming compressed behind, and 

 its least depth about | its length measured to rudimentary adipose 

 fin-spine. 



Head short, well depressed, and profiles similar. Snout broad, 

 depressed, its length f its basal width. Eye moderate, lateral, and 

 its center about last fourth in head. Eyelids free. Mouth rather 

 t)road, transverse, and placed about first f in snout. Disk rounded, 

 apparently \yith entire edges, and surface with a few papillae on lower 

 lip. Teeth slender, simple, uniserial, long, and slightly bent, com- 

 pressed tips blunt. Inner buccal folds apparently broad. Tongue 

 broad, fleshy, little distinct at present. Each lateral corner of buccal 

 disk with short triangular fiesh}^ barbel, apparently less than half 

 of eye in length. Nostrils together, simple pore within depression 

 on top of head just before front edge of eye, extent of depression 

 each less than half of eye, and bony internasal region trifle more 

 than eye. Interorbital broadly and slightly convex. Occipital 

 process broadly triangular. Opercle large and very porous. 



