No. 3.] MUSCLES AND NERVES IN AMIA CALVA. Jan 
the first spinal nerve the nerve that lies between that arch and 
the hind end of the skull. 
In front of the first spinal dorsal arch, defined as above, 
between it and the occipitale laterale, there are still, in Amia, 
two dorsal arches, the occipital arches (DA?) of Sagemehl. 
The anterior of these two arches rests in the hollow between 
the two transverse wedge-shaped ridges on the cartilaginous 
strip on the dorsal surface of the basioccipital, the posterior one 
in the hollow between the posterior ridge and the dorsal cartila- 
ginous process on the first vertebra. These transverse occipital 
ridges are, therefore, dorsal vertebral processes, morphologically 
similar to the dorsal processes of the vertebrae. The posterior 
occipital arch is fused with the posterior face of the posterior 
process, while the anterior arch is fused, not with the posterior 
face of the anterior process, but with the hollow between the 
two processes. This hollow lies, as already stated, in the 
plane of the slight groove or line that separates the posterior, 
vertebra-like end of the basioccipital from the rest of that 
bone. 
Between the dorsal end of the two pieces forming each occipi- 
tal arch, there was, in all young specimens, a processus spinosus 
(PSP), performed, in part at least, in cartilage, as are the cor- 
responding processes on the spinal arches. In some of the 
adult specimens there were, also, two such occipital processes, 
as Sagemehl has already stated (No. 104, p. 190). In others 
there was but one, the process, or plate (Sagemehl), in such cases, 
having two upper ends or spines, one directed backward and 
the other forward. No separate piece was found, in any speci- 
men, between the first spine and the occipitale laterale, as 
shown in Sagemehl’s Fig. 3 (No. 104), and described by him in 
a footnote to page 190. Sagemehl suggests (No. 107, p. 524), 
that one of these two occipital spines may fuse with, or become 
incorporated in, the skull of teleosts and Amniota, and there 
give origin to the supraoccipital. He also makes the general 
statement (No. 107, p. 526), that the latter bone is found in all 
vertebrates in which one or more nerves issue from the cranium 
posterior to the vagus. This is certainly not entirely true, for two 
such nerves issue from the cranium of Amia, and Amia does 
