212 DESCRIPTIVE CATALOGUE OF AUSTRALIAN FISHES, 



Genus Arius, Bleek. 



Adipose fin of moderate length or short ; a short dorsal fin with 

 a pungent spine and seven soft rays ; anal fin rather short. Head 

 osseous above ; barbels six, four at the mandible, no nasal 

 barbels. Teeth on the palate fixed, the upper jaw longer. Eyes 

 with a free orbital margin ; the anterior and posterior nostrils 

 placed close together, the posterior with a valve. Caudal fin 

 forked ; ventral with six rays, attached behind the vertical from 

 the dorsal. Gill-membranes not confluent with the skin of the 

 isthmus, with free posterior margin. 



Tropical regions. 



818. Arius thalassinus, Kupp. 



Gunth., Cat. Fishes V., p. 139.— Bleek., Atl. Ichth. Silur., t. 61. 



D. 1/7. A. 16-17. P. 1/11. Vert. 18/27. 



The height of the body is contained from four times and three- 

 quarters to five times and two-fifths in the length, (without 

 caudal), the length of the head four times and a-quarter or three 

 and a-half . Head much broader than high ; snout obtuse in 

 young specimens ; the adult fish with the upper jaw pointed, 

 and projecting much beyond the lower. The teeth on the palate 

 are villif orm and form a pair of more or less separate subtriangular 

 patches, each of which is composed of three portions. The 

 maxillary barbels extend to the opercles or to the pectoral fin. 

 Crown of the head granulated ; occipital process triangular, 

 rather longer than broad, elevated in its middle into a longitudinal 

 ridge ; the basal bone of the dorsal spine is small, crescent- 

 shaped. Dorsal spine of moderate strength, granulated in front, 

 slightly serrated behind ; its length equals that of the head 

 without snout ; the dorsal rays are as high as the body. Adipose 

 fin very short. Pectoral spine stronger, and but little shorter 

 than the dorsal spines. 



Torres Straits. Port Jackson. 



