1915.] NATURAL SCIENCES OF PHILADELPHIA. 237 



Length 56 mm. (caudal damaged). 



Type, No. 21,922, A. N. S. P. Peruvian Amazon. 1873. J. 

 Orton. Received from E. D. Cope. 



The above example was formerly identified with the preceding 

 species, but is here allowed distinct provisionally, for if simply a 

 variant is quite anomalous. The type of H. psilogaster is larger 

 than the smallest example of H. thoracatum, and it has but two rows 

 of ventral scutes, the space between being naked. 



('FtAoc, naked; r^'^~'OP, stomach.) 



DIAPELTOPLITES subgen. nov. 

 Type Hypoptopoma g'ulare Cope. 



Differs from the subgenus Hypoptopoma Giinther, as here under- 

 stood, in the ventral armature consisting largely of two series of 

 plates, though a single plate interposed between the first pair. 



The species embraced in this subgenus are H. gulare Cope, H. joberti 

 (Vaillant) and H. steindachneri Boulenger. The subgenus Hypop- 

 topoma contains only H. tJioracatuyn Giinther and H. psilogaster, 

 described previously. 



(Jfa, divided; -iXrri^ shield; o-Xt-rj?^ armed; with reference to the 

 double series of shields on the belly.) 



Hypoptopoma gulare Cope. 



Proc. Amer. Philos. Soc. Phila., XVII, 1878, p. 679. Peruvian Amazon. 

 No. 21,477, A. N. S. P., type. Peruvian Amazon. J. Orton. 



Otooinclus vestitus Cope. 



Proc. Acad. Nat. Sci. Phila., 1871, p. 83, PI. 4, fig. 2. Tributary of Ambyiacu 

 River. 



Nos. 8,283 and 84, A. N. S. P., cotypes. Tributary of Ambyiacu 

 River, Ecuador. J. Hauxwell. 



Otocinclus flexilis Cope. 



Proc. Amer. Philos. Soc. Phila., XXXIII, 1894, p. 97, PI. 8, figs. I3a-b. 



Rio Jacuhy. 

 Otocinclus fimbriatus Cope, I.e., p. 98, PI. 9, figs. IQa-b. Rio Jacuhy. 



Nos. 21,622 to 26, A. N. S. P., cotypes of 0. flexilis Cope. Rio 

 Jacuhy, Brazil. H. H. Smith. 



Nos. 21,752 to 55, A. N. S. P., cotypes of 0. fimbriatus Cope. 

 Same data. This nominal form appears to be a condition of greater 

 age. 



Microlepidogaster nigricauda (Boulenger). 



Rio Jacuhy, Brazil. 



