430 CALIFORNIA ACADEMY OF SCIENCES. 



Liposarcus altipinnis Giinther, v, 239, 1864 (Eiver Cupai) = young. 

 ? Liposarcus scrophus Cope, Proc. Acad. Nat. Sci. Pbilad. 1874, 136 



(Nauta); id. Proc. Am. Philos. Soc. xvii, 681, 1878 (Nauta). 

 Habitat: Amazon; Solimoens and tributaries; from Gurupa to 

 Nauta. 



This seems to be the most abundant species of the 

 Plecostomince inhabiting the Amazon. 



Heavy forward, the depth 1J in the width, rapidly ta- 

 pering from the dorsal spine to the slender tail. Profile 

 steep; occipital with an abrupt, high crest; a slight de- 

 pression between the middle of the interorbital and the 

 edge of the orbit; temporal keels more or less strongly 

 marked. Snout pointed, its tip naked in the young, 

 granular in the adult. 



Interopercle freely movable, with a few movable mar- 

 ginal spines. 



Orbit large, 3-4J in snout, 6-7| in head, 2J-3f in the 

 interorbital. 



Ventral surface entirely naked in young, entirely gran- 

 ular in adult examples. 



Lateral scutes with a median series of enlarged spines. 

 Posthumeral keel strong anteriorly. 



Distance of the dorsal fin from tip of snout equals the 

 base of the fin or shorter by 2 interradial spaces. 



Dorsal fin variable in height, its greatest height al- 

 ways much less than its length. 



Caudal obliquely emarginate, the outer rays thick, 

 produced. 



Pectoral extending beyond base of ventral fins. 



Ventral beyond base of anal. 



Light or dark brown, everywhere covered with large, 

 darker spots, interspersed with smaller spots of similar 

 color; spots on the belly large and regular; all the fins 

 closely covered with large dark spots, leaving narrow 

 reticulating lines between; the upper caudal ray some- 

 times yellowish. 



