FISHES OF THE FAMILY LOEICAEIIDJE. 297 



Length of head 3-^-3-^ times in the total length. Head If times as long as broad. 

 Diameter of eye 7-9 times in the length of head,-interorbital width about 5 times, 

 length of snout about If times. Supraoccipital with a pair of weak keels ; orbit with 

 a large rounded notch ; snout with a long narrow process, expanded and armed with 

 recurved spines at the tip. Lips and teeth as in the preceding species. 27 scutes in 

 a longitudinal series, 11-13 + 14-16; lateral keels separate throughout, strong; all 

 the scutes in front of the dorsal weakly carinate ; lower surface of head naked ; 

 abdomen covered with a few large plates. Fins as in the preceding species. Body 

 with 6 dark cross-bands ; caudal with blackish spots. 



Total length 122 mm. 



R. Amazon. 



13. OXTLOEICAEIA. 



Sturisoma (nomen hybridum) Swainson, Nat. Hist. Fislies, i. p. 337 (1838). 

 Owyloricaria Bleek. Ned. Tijd. Dierk. i. 1863, p. 80. 



Harttia Steind. Sitzb. Ak. Wieii, lxxiv. 1876, pt. i. p. 668; Eigenm. & Eigenm. Occ. Pap. Cal. Ac. 

 i. 1890, p. 385. 



This genus is distinguished from Loricaria by the numerous and setiform teeth and 

 the absence of an orbital notch. In many of the species also the snout has an anterior 

 projection. Vertebra? 5+7 + 25 (in 0. lyra). Ribs present, slender. 



Rivers of S. America. 



In all the species the head has no ridges or prominences, and is evenly convex 

 above ; the lips are papillose, the lower rounded and with short marginal fringes ; the 

 barbel is short. In the species with a rostrum the sides of the head are armed with 

 bristles in the males. 



It seems most convenient to recognise this genus with the present limits. A sub- 

 division based on the presence or absence of a rostrum would result in separating 

 0. brevirostris from 0. guentheri, to which it seems to be at least as closely allied as to 

 0. platystoma. 



Key to the Species. 



I. Snout rounded or pointed, not produced as a rostrum. 

 Abdomen naked, except for the lateral series of plates and a pair of 



anal plates 1.0. loricariiformis Stdr. 



Abdomen covered -with numerous small plates, arranged in 8-10 irre- 

 gular series between the lateral series ; a pair of anal plates . . 2. O. platystoma Gthr. 



Abdomen covered with plates, arranged in 3 series between the lateral 



series 3. O. brevirostris Eigmn. 



II. Snout produced, forming a distinct rostrum. 



A. Pectoral spine extending nearly to base of ventral or a little beyond. 

 Length of snout li times in that of the head, diameter of eye 7§ times 



9 t> 9 



