90 MEMOIRS OF THE CARNEGIE MUSEUM. 



An ovate spot at the end of the caudal peduncle, continued a little way on 

 the middle rays; tip of dorsal variously dusky, a distinct narrow, silvery, lateral 

 band. 



Genus XXI. Odontostilbe^" Cope. 

 Odontostilbe Cope, Proc. Am. Phil. Soc, 1870, p. 566. 



Type: Odontostilbe fugitiva Cope. 



Teeth notched, in a single series, those of the premaxillary and mandible 

 similar, with a large median point and smaller lateral points; maxillary with a 

 few broad-tipped teeth; third suborbital in contact with the pre-opercle below; 

 adipose fin well-developed; origin of anal under end of dorsal; caudal naked; 

 lateral line complete; scales with few radial striiE; interhsemals feeble, not pro- 

 jecting. 



Minute fishes found from Panama and Trinidad to the La Plata and the 

 Peruvian Amazon. 



But few of the species of this genus are distinguishable at sight. 0. melandeia 

 may be distinguished by the absence of a proper caudal spot; paraguayensis ajid 

 madeirce by their deep form, they are quite similar; drepanon by its filamentous 

 fin-rays. 0. microcephala and fugitiva are very similar. 0. hastata stands quite 

 alone, but looks hke microcephala. 0. microcephala differs from Holesthes heterodon 

 largely in the structure of the teeth of the lower jaw. 



It is possible that 0. hastata and 0. melandeia do not belong to this genus. 



Key to the Species op Odontostilbe. 

 a. Caudal in the male with a pouch covered by scales just below the shortest rays at the middle. Eye 3; 

 A. 18-21 ; raj^s of lower caudal lobe of male with retrorse hooks, an intense well circumscribed spot on the 



caudal peduncle 48. hastata Eigemnann. 



aa. Caudal naked in the male. 



6. A large conspicuous caudal spot; teeth large; 5-7 in the premaxillary, 1-4 in the maxillary, 

 c. Male with the outer ventral and first developed dorsal rays filamentous. D. 10 to 12. 



49. drepanon Fowler. 

 cc. Male without filamentous rays. 

 d. Dorsal with 10 or 11 rays. 



e. Depth about 3.25; A. 22-34; scales 35 to 37; mouth minute, maxillary half the length 



of the eye 50. fugitiva Cope, 



ee. Depth 3 to 4; A. 18-22, scales 34r-37; mouth moderate, maxillary more than half the 



length of the eye 51. microcephala Eigenmann. 



eee. Depth 2.5 to 2.75; A. 22-25; scales 33 or 34; caudal spot imUstiuct.. .,52. pulchra Gill. 



eeee. Depth 2.6 to 3; A. 21-24; scales 32-35; mouth minute. Maxillary half the length of 



the eye 53. paraguayensis Eigenmaun & Kennedy. 



^^ oSoiis, 6 = tooth; o-riX/St), 17 = a lamp, possibly in allusion to the brilliant teeth. 



