88 PROCEEDINGS OF THE NATIONAL MUSEUM. vol. xxxi. 



Regarding P. tenuis^ We3'enbergh states that he is inclined to believe 

 it to represent a new genus, but the lack of literature forces him to 

 treat the subject with caution. He therefore provisionally describes 

 the species under the generic name of Trychcmiycteriis. The most 

 important specific characters given b}' him are the following: 



D. 6; A. 5; P. 8; V. 6; C. 10. 



Color: Dusky gray, with dull yellow belly, and yellowish fins; base of caudal 

 dusky. 



It was found in a little lake in the Sierra de Cordoba, near the town 

 of Cruz-del-Eje. Length of largest individual 3 cm. (about 1.18 inches). 

 The figure represents a fish similar to ours in color. 



The most important points given in Weyenbergh's description of 

 P. cordovensis are as follows: 



D. 7; A. 5; P. 8; V. 5; C. 14. 



Color: Clear sepia; fins colorless excepting middle of caudal which is dusky or 

 plumbeous; some have dusky spots or wavy markings on the back and are somewhat 

 dusky about the lateral line; belly pale; top of head with a dusky spot between the 

 eye and upper barbel; this barbel dusky, the others pale. Length of largest indi- 

 vidual 8 cm. (about 3.1:^ inches). 



Regarding the habitat and habits of the fish Weyenbergh says that — 



This little fish is caught in the Rio Primero and in the channels of Cordoba, 

 where it searches for aquatic insects, especially larvte of the friganids. It moves 

 about amongst the rocks with remarkable swiftness, emptying the shells of the larvse 

 mentioned, constructed of gravel and stuck to the larger rocks; it is diflftcult to catch, 

 since it disappears and conceals itself under the rocks and in the mud at the first 

 sign of danger. 



Description of the larger of our specimens: Total length 1.75 inches. 

 Head 4.75 in length without caudal; eye 10.6 in head; snout 2.06; 

 longer maxillary barbels about 2 in head; nasal barbel scarcely reach- 

 ing front of e^^e; depth of bod}^ 7.60 in length without caudal; first 

 pectoral ray somewhat produced, its total length 1.23 in head; length 

 without produced ray 1.15 in head; base of ventral a little in advance 

 of origin of dorsal; D. 9, its base 2 in head; A. 6, its origin immedi- 

 ately under last ray of dorsal; length of anal base 'yl^.^SQ in head; dis- 

 tance from posterior base of anal to lower base of caudal ecpialing 

 length of head; caudal emarginate. 



Small example: Total length 1.62 inches. Head 5; eye 7; snout 

 2.80, and longest maxillary barbel 2 in head; nasal barbel just reach- 

 ing front of eye; depth of body 8.75 in length without caudal; first 

 pectoral ray somewhat produced, about 1.16 in head; without pro- 

 duced ray, pectoral fin 1.10 in head; base of ventral somewhat in 

 advance of origin of dorsal; D. 9, its base 1.75 in head; A. 6, its 

 origin under posterior end of dorsal, its base 2.11 in head; distance 

 from posterior base of anal to lower base of caudal a little greater 

 than length of head. 



