ElGENMANN : THE EXPEDITION TO BRITISH GUIANA. 7 



maxillary with eight teeth, each with two nearly parallel cusps, of 

 which the inner one is much the longer. 



Origin of the dorsal above the middle of the ventrals, the first ray, 

 not much more than half as long as the second, not spinous, the highest 

 ray a little less than the snout ; spine of the adipose -§■ of the length of 

 the snout, covered with a few spines, tip of spine nearly reaching end 

 of base of adipose part of the fin ; caudal rather deeply emarginate, 

 the lower lobe the longer ; origin of anal half way between tip of dorsal 

 and origin of adipose ; outer ventral ray very thick and fleshy, covered 

 with spines, its base much wider than that of the rest of the fin, reaching 

 a little more than half way to anal ; length equal to the snout ; pec- 

 torals reaching to near tip of ventrals, its spine not much larger than 

 the rest of the rays, with a few prickles. 



Naked except for a double series of plates along the ventral surface 

 of the caudal peduncle from near the tip of the anal and curved up on 

 either side of the caudal to the base of the middle rays ; about fourteen 

 platelets along the middle of the sides from above the origin of the 

 anal to the base of the middle caudal rays, widest above the tip of the 

 anal where they are a little wider than the eye ; a double series of 

 plates on the back, beginning on either side of the spine of the adipose 

 to the caudal ; outer caudal rays with prickles, a few spinelets on the 

 caudal. 



A dark band from the eye forward, increasing in width to above the 

 base of the maxillary : back and upper part of sides marbled ; caudal 

 dark, the outer rays lighter. 



Genus Loricaria Linnaeus. 



Loricaria microdon sp. nov. 



? Loricaria acuta (non Valenciennes) Miiller & Troschel, in Schom- 

 burgk. "Reisen in Brit. Guiana"; III, 631. (Sand bars of the 

 Rupununi.) 



This species is closely allied to, if not identical with, acuta. Regan 

 gives the lower lip of acuta as entire. 



Type, 90 mm. (No. 1507 Carnegie Museum Catalog of Fishes.) 

 Rupununi. 



Cotypes, two, 76 and 112 mm. to tip of middle caudal ray. (I. 

 U. ) Rupununi. 



Head 4-4! ; width of head if— 1-}- in its length; eye 6, equal to 

 interorbital ; snout 2 -f in the head ; width at first anal ray 5-i— 



