148 SILURID^. 



to the baite of the occipital process. Teeth on the vomer separated in 

 the middle by a short interspace, forming a pair of 

 small subquadrangular patches which are confluent 

 with those of the palatines. The latter are much 

 longer than broad, elliptical. The band of inter- 

 maxillaiy teeth is five and a half times as broad as 

 long. The maxillary barbels extend nearly to the 

 end of the head, and are about twice as long as the outer ones of the 

 mandible. Crown of the head and nape finely granular ; occipital 

 process broader than long, with a prominent ridge along its middle. 

 The basal bone of the dorsal spine is small, with a few fine granules. 

 Dorsal spine of moderate strength, more than half as long as the head, 

 serrated along both edges ; the first soft ray is as high as the body. 

 Adipose fin rather shorter than dorsal. The upper caudal lobe is 

 the longer, two-ninths of the total length. Porus axillaris present. 

 Ventral fin shorter than pectoral. Sides of the body silvery ; basal 

 half of the inner side of the paired fins black. 



Central America. 

 a. Pine specimen, 12 inches long. From the Haslar Collection. 

 Collected by Dr. Seemann. 



15. Arius surinamensis. 



Hexanematichthys surinamensis, Bleek. Versl. ^ Medechel. Akad. Wet. 

 Amsterd. 1862, xiv. p. 380. 



B. 5. D. 1/7. A. 18. P. 1/9. 



The height of the body is one-sixth of the total length (without 

 caudal), the length of the head two-sevenths ; the greatest width of 

 the head is three-fourths of its length. Occipital process without 

 conspicuous keel along its middle, not longer than broad, extending 

 on to the small basal bone of the dorsal spine. The teeth on the 

 palate form four contiguous patches or bands, the lateral bands being 

 broader and longer than the anterior. The maxillary barbels extend 

 to the base of the pectoral, the outer ones of the mandible somewhat 

 beyond the gill-opening. Dorsal spine strong, half as long as the 

 head, slightly serrated along both edges ; adipose fin as long as the 

 dorsal, its length being less than one-third of the distance between 

 the two fins ; pectoral spine longer and stronger than that of the 

 dorsal fin ; ventral fins much shorter than pectorals. Caudal deeply 

 forked, with the upper lobe longer. {Bl.) 



Surinam. 



16. Arius proops. 



Bagrus proops, Cuv. 8,- Val. xiv. p. 457. 



D. 1/7. A. 19. P. 1/11. 

 The eye is thrice as remote from the praeopercular limb as from 

 the end of the snout ; jaws equal in length anteriorly. The teeth on 

 the palate are divided into six portions, the two posterior being large 

 and triangular. The maxillary barbel extends beyond the root of 

 the pectoral. The occipital process is short, one-eighth of the length 



