eigenmann: the FRESHWATER FISHES OF BRITISH GUIANA 219 



Thirteen specimens, 97-98 mm. Chipoo Creek. (C. M. Cat. No. 1577a-e 

 and 1583a-6; I. U. Cat. No. 11989.) 



One specimen, 105 mm. Packeoo Falls. (C. M. Cat, No. 1578.) 



Seventy-four specimens, 58-109 mm. Gluck Island. (C. M. Cat. No. 

 1579a and 1580o-o; I. U. Cat. No. 11990.) 



Five specimens, 61-120 mm. Kumaka. (C. M. Cat. No. 1581a-6; I. U. 

 Cat. No. 11991.) 



Three specimens, 114-124 mm. Mud creek in Aruka. (C. M. Cat, No. 

 1582a; I. U. Cat. No. 11992.) 



One specimen, 158 mm. Botanic Garden, Georgetown. (C. M. Cat. No. 

 1584.) 23 



I have also seen the specimens in the Leiden Museum and the Museum at 



Amsterdam. 



25-26 

 Head 3.5-4; depth 3.16-3.66; D. 1,8; A. 1,6-8; plates ^-^. 



There is considerable variation in shape and color. Snout depressed, more 

 pointed than in thoracatum. Eye 5.5-6 in interorbital; nuchal plates as wide as, or 

 half as wide again, as the plates following them, which are notched to receive the ful- 

 crum of the dorsal; inner rictal barbels extending past origin of ventrals, sometimes 

 past their tip. Four to six (in Aruka River specimens) or seven to eight azygous 

 plates between the lateral plates in front of the adipose dorsal ; four pairs of plates 

 meet behind the dorsal ; depth in front of the adipose fin in some of the Chipoo speci- 

 mens equals the length of the head, but more than an orbital diameter less than the 

 head in Gluck Island specimens; dorsal rounded; caudal slightly emarginate when 

 closed, truncate when opened. Sides spotted or mottled; ventral surface white, with 

 more or less conspicuous black spots; dorsal and caudal spotted, the latter usually 

 with a light bar at the base, the Gluck Island specimens with a broad dark median 

 band, the tip of the caudal dusky. 



Two specimens in the Amsterdam Museum have the coracoids meeting along 



their entire length below. 



Corydoras Lacepede. 



Corydoras Lacepede, Hist. Nat. Poiss., V, 1803, 145 (geoffroyi = punctatus). 



Hoplisoma Swainson, Class. Fishes, Amph., and Rept., II, 1839, 304 (punctata). 



Hoplosoma Gill, Ann. Lye. Nat. Hist. N. Y., VI, 1858, 402 {punctata). 



Gasterodermus Cope, Proc. Am. Philos. Soc, XVII, 1878, 681 (type ?). 



Type, Corydoras geoffroyi Lacepede. 



Characters as given in the key. 



23 In this specimen the caudal is nearly uniform beyond the lighter bar at its base and there are but 

 five azygous plates which correspond to paired plates. 



