4392 Julia B. Platt 
“ 
dorsal extremity of the occipital arch has also united with the inner, 
posterior, dorsal, corner of the capsule and from the cartilage formed 
by this union a point reaches dorsalwards towards the Anlage of a 
cartilage which for a short distance roofs the brain. Gaupp (93) — 
calls this roofing cartilage tectum synoticum, since the name 
hitherto employed (PARKER ’76), oceipitale superius, belongs 
properly to a bone, and moreover to a bone not found in the Am- 
phibia. As the relations of this cartilage in Necturus make it 
appear to me desirable that the cartilage be designated by a name 
which associates it with the occipital arch rather than with the 
auditory capsule, Prof. GAupp has suggested that I call the cartilage 
interoceipitale, and I accept the suggestion. 
The independent origin of the interoccipitale (tectum syno- 
ticum) is noted by Gaupp (93), who seems, however, not to have 
found in the Amphibia which he studied, what is true for Nec- 
turus, namely, that the cartilage in question is not only independent 
in origin, but also paired. In Necturus 19 mm long, the Anlagen 
of the interoccipitale are still prochondral. STöHr (80), who 
describes the roofing cartilage in Triton as connecting the auditory 
capsules, also demurs at the appellation occipitale superius. My 
reasons for preferring a name which associates the cartilage with 
the occipital arch are given in the following division of this paper 
(pages 435, 436). 
The procartilage at the base of the first neural arch of the 
spinal column is primarily separate from the procartilage of the 
basicranial plate, but as cartilage begins to form in this arch, the 
prochondral Anlage at the base of the arch extends forwards and 
unites with the procartilage of the basal plate in that region, ad- 
joining the chorda and median to the base of the occipital arch, 
which remains unchondrified at the time when the occipitai arch is 
converted into cartilage. This connecting prochondral tissue has 
received a special name both from StöHr and Gaupp, being called 
by the former, intervertebro-oceipital tissue, and by the latter 
occipito-vertebral tissue. The tissue in question precedes the 
formation of a cartilaginous extension from the base of the first 
neural arch, which grows forwards at the side of the chorda, ulti- 
mately appropriating the posterior part of the prochondral tissue 
that lies between the base of the occipital arch and the chorda. 
In the embryo of 19 mm, a complete fusion is found between 
the cartilage of this anterior extension from the first neural arch 
no. 7, & zu ee 
