On Fishes from the River Ucayali, Peru. 281 



XXXIV. — Fishes from (he River Ucayali, Peru, collectedly 

 Mr. Mounsey. By C. Tate Kegan, M.A. 



(Published by permission of the Trustees of the British Museum.) 



1. Tetragonopterus ovalis, Giinth. 



2. Gastropelecus sternicla, Linn. 



3. Callophysus lateralis, Gill. 



4. Sorubim lima, Schneid. 



5. Rhamdia mounsey i, sp. n. 



Depth of body 5 to 6 in the length, length of head 3£ to -4. 

 Breadth of head 1£ to 1^ in its length, length of snout 2f 

 to 3, diameter of eye 5^ to 7, interorbital width 2f to 3£. 

 Jaws equal anteriorly or the lower a little shorter than the 

 upper ; width of mouth nearly § width of head. Maxillary 

 barbel extending beyond anal fin. Occipital process extending 

 about | of the distance from its base to origin of dorsal fin. 4 or 

 5 gill- rakers +2 or 3 rudiments on lower part of anterior arch. 

 Dorsal I 6 ; spine slender ; fin rounded. Length of adipose 

 fin 2| to 3 j? in length of fish. Anal 9-11. Humeral process 

 not reaching middle of pectoral spine, which is § to § the 

 length of the fin, or ^ to § the length of head. Pelvics in- 

 serted below or a little behind last dorsal ray, sometimes 

 reaching anal. Caudal deeply notched. Least depth of 

 caudal peduncle 2^- to 2§ in length of head, 1^ to If in 

 distance from anal to caudal. Greyish; a lateral stripe; 

 fins dusky, the dorsal pale at the base. 



Seven specimens, 75 to 135 mm. in total length. 



6. Callichthys ihoracatus, Cuv. & Val. 



7. Corydoras elegans, Steind. 



8. Xenocara cirrhosum, Cuv. & Val. 



9. Ilypoptopoma carinatum, Steind. 



10. Loricariichthys ucayalensis, sp. n. 



Length of head a little more than £ that of the fish. 

 Breadth of head 1£ in its length, diameter of eye 7 to 8£, 

 interorbital width 4£ to 4§, length of snout 2 to 2i. Snout 

 rounded ; head smooth ; orbital notch deep and broad. 



