AND ON THE CLASSIFICATION OF FISH. 535 
from the Clupee. Their difference depended upon the absence 
of the pseudo-branchie in the former. Some species of the 
genus Megalops, obtained from Rich. Schomburgk and Dr. 
Peters, have convinced me that the pseudo-branchiz in this 
genus are evanescently small, and excited a doubt in my mind 
concerning the Clupesoces; I consequently last summer commu- 
nicated my views to the Prince of Canino, that these families 
were probably not good. Since that time I obtained Gnatho- 
bolus, and found that this genus, which is so closely related to 
Notopterus, differs from the former in the possession of pecti- 
nated pseudo-branchiz. It is thus certain that the Clupesoces 
must be given up, that they belong to the Clupeide, and do not 
form even a distinct group. To the Clupeide belong Clupea, 
Pristigaster, Alepocephalus, Gnathobolus, Notopterus, Engraulis, 
Thryssa, Amia, Megalops, Elops, Lutodeira, Hyodon, Butirinus, 
Chirocentrus, Stomias, Chauliodus, Heterotis, Arapaima and 
Osieoglossum. Since the last communication I have examined 
Amia and Chauliodus in Paris; neither have pseudo-branchiz. 
The true Eels, with an air-duct to the swimming-bladder, are 
alone to be referred to the Anguillares; whilst Ophidie are re- 
moved to the order Anacanthini. But even the Anguillares 
must be separated into the Murenoidei, Symbranchii and Gym- 
notini. In the former, as we know, the ova and semen pass 
together into the abdominal cavity, and through abdominal aper- 
tures, as in the Cyclostomi, and the ova in the Salmonide. How- 
ever, I find in the Symbranchii (Symbranchus and Monopterus), 
and in the Gymnotini (Gymnotus, Carapus and Sternarchus), 
deferent canals and pouched ovaries continuing, as in most 
osseous fishes, in the oviducts. The families of the Eel-like 
Physostomi may generally be separated readily by the jaws. 
In the Murenoidei the mouth is bounded in its entire length by 
the intermaxillary bones only, and the upper jaw, which is small 
from imperfect development, is imbedded in the flesh. These 
fishes have no cecum, but a blind sac to the stomach. In the 
Symbranchii (Monopterus, Symbranchus, Amphipnous).the inter- 
maxillary bone also extends to the angle of the mouth, the upper 
jaw accompanies it to the same spot. Their stomach has no 
blind sac nor any cecum. The intestine is quite straight, and 
is accompanied to its termination by the liver, which is ex- 
tremely elongated. In the Gymnotini (Gymnotus, Carapus, 
Sternarchus, &c.) the mouth is bounded anteriorly by the inter- 
