59. ARius. 147 



13. Arius platypogon. 



D. 1/7. A. IS. P. 1/10. 



Closely allied to A. assimilis. 



The height of the body is contained five times and a half in the 

 total length (-without caudal), the length of the 

 head four times; head much broader than high, 

 its greatest width being three-fourths of its 

 length. Eyes of moderate size, their diameter 

 being more than one-half of the extent of the 

 snout, and two-fifths of the postorbital part of 

 the head, which equals the -nddth of the inter- 

 orbital sjiace. The median longitudiiud fonti- 

 cidus on the upper side of the head extends to 

 the base of the orci/jital process. Teeth on the 

 palate continuous ; however, three portions may 

 be distinguished : the central one, which is subpentagonal, broader 

 than long, and notched anteriorly ; and one on 

 each side, which is subtriangular, and much 

 larger than the eye. The band of intermaxil- 

 lary teeth is five times as broad as long. The 

 maxillaiy barbels are comjn'essed in theii* basal \ / 

 half and extend nearly to the middle of the ^ 

 pectoral fin, the outer mandibulary barbels nearly to its root. 

 Crown of the head and nape finely granular ; occipital process 

 much longer than broad, with a low, linear median ridge. The 

 basal bone of the dorsal spine is very small, with only a few 

 granules. Dorsal spine rather strong, a little shorter than that of 

 the pectoral fin, three-fourths of the length of the head, and serrated 

 along both edges ; the first soft dorsal ray is higher than the body. 

 Adipose fin shorter than dorsal. The upper caudal lobe is the longer, 

 its length being contained four times and a third in the total. Porus 

 axillaris present. Ventral much shorter than pectoral, which is 

 nearly as long as the head. Sides of the body silvery ; the inner 

 side of the paii-ed fins black. 



Guatemala. 



a-d. Fine specimens (11| inches long). San Jose. From the Col- 

 lection of Messrs. Salvin and Godmau. 



14. Arius seemanni. 

 D. 1/7. A. 19. P. 1/10. 



Closely allied to A. assimiJis. 



The height of the body is contained four times and a half in the 

 total length (without caudal), the length of the head thrice and a 

 third : head much broader than high, its greatest width being cipial 

 to its length without snout. Eyes of moderate size, much nearer to 

 the end of the snout than to that of the operculum ; the length of the 

 snout is three-fifths of the width of the interorbital space. The 

 median hnffitmlinal fonticidus on the upper side of the head extends 



l2 



