90 



Pisces. 



1. Arges hrachycephalus, n. sp. 



2. Pygidium {Trichomycterus, Val.) dispar, Tschudi. In the 

 figure, given in the ' Fauna Peruana,' the ventral and dorsal fins are 

 too far advanced tovpards the head. 



3. Tetragonopterus penianus, Miiller. 



4. Leporinus millleri, n. sp. 



Nearly all the specimens on which the above list is founded, have 

 been procured for the collection of the British Museum. Having 

 already described the new species of Snakes and Batrachians, I here 

 give an account of one Saurian and of the new Fishes. 



MiCROPHRACTUS, n. g. {Hoplurid(je) . 



Fingers and toes slender, not dilated. Head above covered with 

 small irregular shields, without any distinct larger one. Body 

 above with very small granular scales, those along the middle of the 

 back with a distinct keel ; scales of the belly imbricate, smooth. 

 Tail rounded, of moderate length, tapering, with rings of oblong 

 scales, each with a strong keel in the diagonal line ; a very low crest 

 along the back of trunk and tail. No femoral nor prseanal pores. 

 Tympanum distinct ; a fold on each side of the throat. No palatine 

 teeth. 



MiCROPHRACTUS HUMERALIS, U. Sp. 



Diagnosis. — Above bluish green, marbled with dark brown ; round 

 the shoulder a black band, lighter-edged, interrupted on the verte- 

 bral line ; beneath greenish-yellow ; throat marbled with bluish. 



Description. — The head is rather short and high, above spherical, 

 with the interspace between the eyes of moderate width and flat ; the 

 muzzle is rather short, blunt and rounded in front. The nostril is 

 directed vipwards, round, situated near the outline of the upper sur- 

 face, rather prominent, and formed by a tubular opening of a single 

 small shield. The eyes are of moderate size, with round pupil, not 

 very prominent above the level of the crown. The ear is on the same 

 level with the cleft of the mouth, larger than the eye, irregularly 

 elliptic, and in front bordered by a fringed fold of the skin. All the 

 upper surface of the head is covered by many small shields, irregu- 

 larly arranged and smooth ; they are smallest on the posterior part of 

 the occiput, and on the outer and front edges of the upper eyelid. 

 Such shields occupy the loral region also, the cheeks being covered 

 with granular smooth scales, as the sides of the neck. The upper 

 jaw is bordered in front by a broad, low labial, with a short upper 

 prominence towards the forehead ; the side of the upper jaw is 

 covered by only four narrow and elongate shields; above this series 

 is situated another one of still narrower and more irregular shields ; 

 between this series and the eye is a long sword-shaped shield, bor- 

 dering the orbit from beneath. The lower front labial is anteriorly 

 rounded, and has laterally two sides for the symphysis with two 

 shields or with two series of shields, which, somewhat divergent, are 



