273 
or conical in one, two or three groups on each side. Gill- 
membranes united, connected with the isthmus but with a 
free posterior margin. 5—g branchiostegals. 
Fig. 106. Arius thalassinus (Riipp.). 
Synopsisvef the specttes. 
I. Teeth on the palate granular. 
A, Teeth in four groups (the anterior groups some- 
times rudimentary). (Aviodes Blkr.). 
I. posterior patches in a broad oval, conver- 
ging behind. 
a. anterior patches well developed, sides of 
occipital process'convex ...... . .. A. erossocheilus p. 276. 
4. anterior patches rudimentary or nearly 
wanting, sides of occipital process straight. 
a, head 3 times in length....... . A, macrocephalus p. 277- 
@. head more than 3 times in length. . 4. argyropleuron p. 278. 
2, posterior patches in a narrow oval, parallel 
or diverging behind. 
a. parallel, occipital process with irregular 
convex sideborders, its hinderhalf trian- 
OMEN? 6 Gy haer lalpepeGnCEC apmome SO Go Ere A, polystaphylodon p. 280. 
d, diverging behind. 
a. occipital process oval. .....-- .. A. leiotetocephalus p. 282. 
INDO-AUSTRALIAN FISHES II. 18 
