26 [March, 



pression in advance of the eye. Jaws equal. Three irregular rows of minute 

 teeth situated behind an anterior and more conspicuous row. Eyes rather lar^e 

 and circular, their diameter being contained four times and a half in the length 

 of side of head. Posterior part of cheeks scaly ; large scales on the opercular 

 apparatus. Anterior margin of dorsal situated in advance of the insertion of 

 ventrals; tip of posterior rays extending a little beyond the tip of those of anal. 

 Insertion of ventrals backwards of base of pectorals ; external soft ray much 

 longer than the others. The caudal forms about the two-ninths of the entire 

 length. 



D XVI. 9. + 1. A V. 6 + 1. C 2. I. 7. 7.1. 3. V I. 5. P 14. 



The scales are quite large ; there being 19-20 rows of them across the line of 

 greatest depth, and eighteen in the lateral line, from upper angle of operculum 

 to where it is interrupted, and eight more beneath on the peduncle of the tail. 

 Ground color brownish, with small bluish spots scattered all over the body and 

 fins. 



Brownsville, Texas (fresh water). Capt. Van Vliet and John H. Clark. 



SILURIDjE. 



AILURICHTHYS, B. and G. Head depressed, subrounded, smooth and un- 

 armed. Two pairs of flattened barbels, a maxillary pair, sometimes very much 

 elongated, and a submaxillary one, always shorter. Velvet teeth on the rnaxil- 

 laries, and a band of similar teeth immediately behind the upper maxillary. An- 

 terior margin of both dorsal and pectoral fins prolonged into a membranous 

 thread, more or less elongated according to the species. An adipose fin opposite 

 the anal. Caudal more or less forked. 



9. Ailurichthys marinus, B. and G. Siluriis marinus, Mitch. Gahichthys 

 parrce, Cuv. and Val., Hist. Nat. Poiss. XV. 1840, 33. Gahichthys marinus, 

 Storer, Synops. 1846, 149. 



Indianola, Texas. J. H. Clark. 



Obs. We refer to the same genus ; Gahichthys gronovii, G. eydouxii and 

 G. blochii, of Cuvier and Valenciennes. 



10. Arius equestris, B. and G. Maxillary barbels extending to the middle 

 of length of pectorals. Head contained four times and three-quarters in the total 

 length. Adipose fin of medium size, and situated opposite to the middle of anal. 

 The latter is concave upon its external margin, and deeper than long. The an- 

 terior margin of dorsal is equi-distant between tip of snout and adipose fin. Tip 

 of pectorals extending as far back as the posterior margin of dorsal. Anterior 

 margin of dorsal thrice as high as the posterior margin ; superiorly that fin is 

 subconcave. Longitudinal diameter of eye contained five times in the length of 

 side of head. 



Br. 5. D I. 7. A 16. C 13. I. 7. 7. I. 12. V 6. P I. 9. 

 Indianola, Texas. J. H. Clark 



JV. 



11. Pimelodus affinis, B. and G. Very closely allied to P. cmruhscens, 

 Rafin. and distinguished from it by a more advanced position of the dorsal fin 

 and a greater elongation of the barbels. The head is contained five times and a 

 half in the entire length. The caudal is about the same length as the head. The 

 length of the anal fin is a little more than the fourth of the length, as in P. c&ru- 

 lescens. The eyes are of medium size, and their diameter contained a little over 

 six times in the length of side of head. 



D I. 6. A 35. C 5. I. 8. 7. 1. 6. V 8. P I. 10. 



Color reddish brown above, silvery white beneath ; occasionally marked with 

 subcircular and small black spots. 



Rio Grande del Norte. J. H. Clark. 



CHARACINI. 



ASTYANAX, B. and G Adipose fin present. Abdominal line not serrated. A 

 double row of teeth on both the upper and lower jaw, and flattened with several 

 conical spines or processes upon their edge. Neither canine nor palative teeth. 

 Dorsal fin above the ventrals. Scales large. 



