CLELAND ON RIBS AND TRANSVERSE PROCESSES. 129 
figured, a very illustrative example is afforded of the transitions of 
series of processes at the commence¬ 
ment of the tail. In this fish, the 
first inferior caudal spine and first 
anal interspinous bone are arranged 
very much as in the pleuronectidae ; 
but, whereas in the pleuronectidae 
the projections of the abdominal 
cavity behind this point are irre¬ 
gularly formed pouches running 
along the sides of the interspinous 
bones, in JVaseus the membrane 
lining the abdominal cavity is dis¬ 
posed in the fore part of the tail as 
it is in the trunk, though the space 
embraced by it is divided vertically 
by the inferior spines; which is 
exactly the arrangement shown by 
Prof. Groodsir to take place in the 
tail of the Crocodile, save that in 
this instance the divided part of the 
cavity contains not muscle, as in the 
case of the Crocodile, but viscera. 
This condition is neither typical of 
the trunk nor of the tail, but is a 
transition form. JVaseus possesses both a superior and a true set of 
ribs ; the former is continued into the tail, but the latter ceases on 
the penultimate trunk vertebra. The bodies of the trunk vertebrae 
also are grooved for the great vessels. The inferior arch of the 
first caudal vertebra, with its spine, is continuous with the borders 
of the groove on the vertebra in front, so that the canal which the 
trunk vertebrae forms incompletely becomes perfect on the first 
caudal vertebra, similarly to the arrangement in LopJiius piscatorius. 
In addition to this, the limbs of the inferior arch are so stout, and 
arise so much from the sides of the body, that they present a certain 
appearance of series with the transverse processes in front, as in the 
generality of fishes. But, besides its inferior arch, the first caudal 
vertebra presents on each side a bifid transverse process quite serial 
with the transverse processes in front, its inferior border lying in 
the prolongation backwards of the visceral wall, and the superior 
point of its bifid extremity giving attachment to a rib of the superior 
series, i. e., to a bone lying in the lateral intermuscular septum. 
This bifid process, therefore, is quite similar to the bifid processes at 
the back part of the trunk of the Conger; yet in series with the 
upper and lower parts of the processes in the Conger we find respec¬ 
tively simple transverse processes in the lateral intermuscular septa 
and inferior spines, while in JVaseus we find bifid transverse process 
and inferior spine co-existing in the same vertebra. 
N. H. K.—1863. K 
