658 Proceedings of the Royal Society 
number of bony plates. The suboperculum is also completely 
absent. The arrangement of the mucus canals on the head is 
similar to that in Polypterus. 
The arrangement of the muscular system corresponds in the two 
genera. In Calamoiclithys, owing to the great increase of the num- 
ber of vertebrae, the number of transverse segments of the great 
body mascle is also much larger. The muscular layer along the 
belly is very thin. 
Viscera . — The oesophagus dilates into a flask-shaped stomach, 
which terminates behind in a cul de sac. From the interior part 
of the stomach, and close behind the entrance of the oesophagus, 
issues the intestine, which, passing first slightly forwards, makes 
almost immediately a turn on itself, and then proceeds straight 
back to the anus. A small coecal appendage, with the apex di- 
rected forwards, is seen in connection with the intestine shortly 
after its backward flexure ; and a little farther down, between this 
and the anus, a spiral valve of about five turns is developed in the 
interior. The liver was in none of the specimens examined very 
voluminous, but much elongated, being continued as a narrow stripe 
the whole length of the abdominal cavity. The gall-bladder is 
distinct, and opens into the intestine immediately after its flexure, 
and in front of the coecum. 
The heart is conformed, as in Polypterus, with muscular bulbus 
arteriosus, which is furnished internally with numerous valves of 
unequal size. The branchial artery gives off first a large lateral 
branch on each side, which divides into three for the three posterior 
gills ; the trunk then bifurcates, giving off a branch for the anterior 
gill of each side. As in Polypterus, the posterior gill has only one 
row of leaflets, and the cleft behind it is wanting. No trace of a 
Pseudobranchia” was found, an organ likewise absent in Polyp- 
terus. The spleen is very long and slender, lying closely along 
the great air-bladder. The air-bladders are two in number, open- 
ing by a common orifice into the lower aspect of the throat, 
behind the gill-clefts. That of the left side is small, being 
only 2|ths inches in length on a fish of 10 inches ; it is closely 
adherent to the side of the oesophagus and commencement of 
the stomach. That of the other side measures 8| inches on the 
same fish, and extends along the whole length of the abdominal 
