CHAPTER XLV 
OPISTHOMI AND ANACANTHINI 
&)|RDER Opisthomi.—The order Opisthomi (omic On, behind; 
@os, shoulder) is characterized by the general traits 
of the blennies and other elongate, spiny- rayed 
fishes, but the shoulder-girdle, as in the Apodes and the 
Heteromi, is inserted on the vertebral column well behind the 
skull. 
The single family, Mastacembelide, is composed of eel-shaped 
fishes with a large mouth and projecting lower jaw, inhabiting 
the waters of India, Africa, and the East Indies. They are 
small in size and of no economic importance. The dorsal is 
long, with free spines in front and there are no ventral fins. 
Were these fins developed, they should in theory be jugular in 
position. There is no air-duct in Mastacembelus and it seems 
to be a true spiny-rayed fish, having no special relation to 
Fig. 652.—Mastacembelus ellipsijer Boulenger. Congo River. (After Boulenger.) 
either Notacanthus or to the eels. Except for the separation 
of the shoulder-girdle from the skull, there seems to be no 
reason for separating them far from the Blennioid forms, and 
the resemblance to Notacanthus seems wholly fallacious. 
Mastacembelus armatus is a common species of India and 
China. In Rhynchobdella the nasal appendage or proboscis, con- 
spicuous in Mastacembelus, is still more developed. Ahynchob- 
della aculeata is ccmmon in India. 
Order Anacanthini—We may separate from the other 
jugular fishes the great group of codfishes and their allies, 
739 
