Eigenmann: South American Silurid.e. 399 



four and a half times; occipital process in contact with the dorsal 

 plate; parietal fontanel narrow, separated bya broad bridge from the 

 frontal fontanel. Maxillary barbel longer than the entire length; in 

 the specimen, which is 55 mm. long, it measures 65 mm., in the speci- 

 men, which is 117 mm. long, it measures 126 mm.; postmental barbel 

 extending about to the middle of the ventrals; adipose fin three to three 

 and a quarter times in the length; first dorsal ray flexible, slightly 

 longer, but coterminous with the second ray, 3.6-3.8 in the length. 

 First pectoral ray pungent, with a very short, soft prolongation, 

 and with about twenty-five recurved teeth on the posterior margin, 

 graduate from the tip to the base, anterior margin with obscure re- 

 curved notches. Length of pectoral spine equals the head without 

 the opercle. Caudal very deeply forked, the longest ray sometimes 

 more than four times as long as the middle ray, the longest ray some- 

 times two and three-quarter times in the length. A black saddle, 

 half or two-thirds as long as eyes, crosses the back in front of the dorsal 

 spine and extends one-third down the sides. No other markings. 



3. Cheirocerus goeldi (Steindachner). 



Pimelodina goeldii Steindachner, Akademischer Anzeiger, Vol. XLV, Feb., 1908, 

 No. VII. 

 72520-^, C. M., 91 -98 mm., to base of caudal, about 1 18-129 ""i"^- "ver 



all. Santarem, Dec. 15, 1909. Haseman. 



This species is very closely allied to P. eqiies. The adipose is 2.7- 

 2.66 in the length and the black saddle is replaced by a small triangular 

 spot in front of the dorsal spine. 



Head 5; depth 6; D. 7; A. 11; eye 4 in the head, interorbital 4; 

 parietal fontanel narrow, with a constriction near its middle, which 

 in larger specimens bridges over. Maxillary barbel longer than the 

 entire fish, postmentals reaching to middle of ventrals. 



First dorsal ray, which is the highest, 3.5 times in the length. 

 Pectoral spine nearly equal to the length of the head, its armature 

 similar to that of C. eques, but the spinules a little larger; a triangular 

 black spot in front of the dorsal spine. This species hitherto has been 

 only known from the type. 



Genus Acentronichthys Eigenmann & Eigenmann. 

 4. Acentronichthys leptos Eigenmann & Eigenmann. 

 5718a-/?, C. M., 31-84 mm., Morretes, Jan. 3, 4, 1909. Haseman. 



