722 ALLIS. [Vou. XII. 
not possess the bone. Sagemehl himself was well aware that 
one such nerve is found in Amia, for he himself first described 
it. Doubting the origin of the bone assigned to it by Sagemehl, 
I am inclined to consider it as primarily of membranous origin, 
developed in connection with the tendinous attachment of 
muscles, as the intercalar evidently is. That it should not be 
developed in ganoids, dipnoids, selachians, or amphibians is not 
singular, if the schema given in Fig. 12, Pl. XXII, is correct. 
The bone is, in that case, simply a late acquisition, and hence 
found naturally, and developed independently, in teleosts and 
Amniota. 
The intermuscular septum that has its attachment on the 
posterior occipital arch runs downward onto the vertebral-like 
end of the basioccipital, and then onto the large ligament that 
arises, rib-like, from that end. The intermuscular septum that 
has its attachment on the anterior occipital arch runs down- 
ward in front of the vertebra-like end of the basioccipital, onto 
the small anterior occipital ligament. 
Starting from the hind end of the skull, partly from the 
cartilage of the skull, and partly from the adjoining median 
edges of the two occipitalia lateralia, and running directly 
backward between the dorsal arches, there is a strong liga- 
mentum longitudinale vertebrale dorsale superior (/vd’, Fig. 9, 
Pl. XXI). In the 50 mm. larva examined in transverse sections, 
there were, immediately below this ligament, between the two 
halves of the last dorsal spinal arches included in the sections, 
two independent pieces of cartilage, one on each side, forming 
a bridge between the arches, and between the ligament and the 
spinal cord. These little pieces are described by Scheel (No. 
109) in Trutta and other teleosts, and are considered by him 
as the “urspriingliche Fortsetzung der Neuralbogen.”’ 
The ligamentum longitudinale dorsale inferior (4vd’, Fig. 18, 
Pl. XXII) starts from the front edge of the dorsal surface of 
the solid end of the basioccipital, and runs backward between 
the dorsal occipital processes, and then between the dorsal 
spinal processes. From it arise, as already described, the little 
lateral projections that fill the indentations in the bases of the 
dorsal arches. 

