ON THE ANATOMY OF FISHES. 
185 
projecting processes (fig. 73). The transverse process of the fourth vertebra 
consists of a thickened anterior part which curves downwards, and for a portion of 
its extent has its anterior face closely applied to the inferior limb of the post- 
temporal, while its free distal extremity furnishes a posterior wall to the socket for 
the clavicle. The remainder of the process is a thin narrow lamina of bone, curving 
at first upwards and backwards, and then slightly downwards to meet a somewhat 
similar but shorter lamina, derived from the anterior margin of the transverse process 
of the fifth vertebra. The latter {t.p}), in addition to the lamina already mentioned, 
consists of a long stout process, which has its free projecting extremity connected by 
a ligament (fig. 73, Igt.) with the larger of the two processes, into which the 
proximal end of the clavicle divides. 
Superficial ossifications thicken the lateral surfaces of the complex and fifth 
vertebral centra, but are interrupted intervertebrally by an irregular interdigitating 
suture. Their dorsal and ventral edges respectively form the inferior lips of cardinal 
grooves, and the lateral margins of a median aortic groove (fig. 73). Small radial 
nodules are suturally attached to the sides of the complex centrum, and a slender 
spicular dorsal lamina (d.L), with the usual relations to the corresponding cardinal 
groove, is prolonged from each nodule and blends with the ventral surface of the 
transverse process of the fourth vertebra. 
The post-temporal has the usual three divisions. The slender inferior limb 
(fig. 73, pt.i.) is largely supported by the thickened and decurved anterior portion of 
the transverse process of the fourth vertebra. Between the inferior limb and 
the stem of the bone there is a deep groove, which is closed behind by the transverse 
process, and converted into a tubular socket for the head of the clavicle. The 
posterior margin of the stem (fig. 75, pt.s.) is coincident with, and closely applied to, 
the similarly curved distal extremity of the same transverse process. The ascending 
process (pt.a) is very slender, articulating above with the supraoccipital and epiotic, 
and nearly meeting the pterotic in front. The proximal end of the clavicle is 
divided into two processes, a slender peg-like process for insertion into the clavicular 
socket, and a strong triangular outgrowth {cl'.) which is directed backwards dorsad to 
the origin of the pectoral fin, and takes the place of the proper posterior process {cl.p.) 
in forming the inferior limit of the contiguous lateral cutaneous area, A strong 
ligament (fig. 73, Igt.) connects the distal extremity of the process with the trans- 
verse process of the fifth vertebra. 
In consequence of the peculiar flattened condition of the head and the adjacent 
portion of the trunk in this genus, the extensive lateral cutaneous areas (fig, 73, l.c.a.) 
are situated rather on the dorsal than the lateral surfaces of the body. Each area is 
peripherally attached to the curved distal margins of the modified transverse processes 
of the fourth and fifth vertebrae above, in front to the posterior margin of the stem 
of the post-temporal, and inferiorly, or rather externally, to the clavicular process 
and to the ligament leading-therefrom to the transverse process of the fifth vertebra. 
MDCCCXail. — B. -1 B 
