328 CYPRINODONTID^. 



the height of the body two-elevenths. Snout rounded, with the 

 jaws equal in lenjjth, somewhat shorter than the eye, which is one- 

 third or two-sevenths of the length of the head. Mandible as long 

 as the eye. Interorbital space quite flat, its width being half the 

 length of the head. Dorsal fin situated far backwards, opposite to 

 the posterior third of the anal ; and its distance from the gill-opening 

 equals double the length of the head. Ventral fins very small, not 

 much longer than the eye, and reaching the vent. Pectoral ter- 

 minating at a great distance from the ventral. Light brownish: 

 body with a longitudinal scries of dark-brown dots, two of the series 

 being very conspicuous. Vertical fins striolated with blackish 

 brown. Generally a black, white-edged ocellus on the upper part 

 of the root of the caudal. 



Rio Negro ; Venezuela ; Trinidad. 



a-b. One inch and a half long. Venezuela. From Mr. Dyson's 



Collection. 

 c. One inch and a half long. Trinidad. Presented by Lechmere 



Guppy, Esq. 



10. ORESTIAS. 



Orestias, Ctiv. ^ Val. xviii. p. 221. 



Ventral fins none. Cleft of the mouth of moderate width, directed 

 upwards, with the lower jaw prominent, and with the upper pro- 

 tractile. Both jaws with a narrow band of small conical teeth. 

 Scales rather small or of moderate size, those on the head and upper 

 part of the trunk frequently enlarged, plate-like, and granulated. 

 Dorsal and anal fins moderately developed, opposite to each other. 

 Sexes not differentiated by modification of the anal fin. Intestinal 

 tract but little convoluted. The gill-membranes of both sides are 

 united for a short distance, and not attached to the isthmus. 



Alpine lakes of the Andes. 



1. Orestias cuvieri. 



Orestias cimeri, Cuv. 8f Val. xviii. p. 225, pi. 532. 



liumboldtii, Ctw. Sf Val. xviii. p. 233, pi. 534 (half-grown). 



B. 5. D. 14-16. A. 18-19. L. lat. 50. 



Body rather elongate than stout. Head twice as long as high, its 

 length being only one-third of the total (without caudal) ; in young 

 specimens it is somewbat shorter. Eye of moderate size, one- fifth 

 of the length of the head in large examples, and one-fourth in 

 younger ones. The snout is produced, rather longer than the eye ; 

 prajorbital nearly square. The scales on the cheek leave a broad 

 ring round the eye and a large space behind the maxillary uncovei'ed. 

 Adult specimens with the scales on the head and the upper part of the 

 trunk granular. The length of the posterior limb of the prfeoperculum 

 is less than two-thirds of that of the lower. Pectoral terminating at 

 a great distance from the vent. The distance between the dorsal and 

 caudnl fins is about equal to the length of the base of the former. 



Lake Titicaca. 



