m 



with in it tlie myocoel (/H.r.) whicli is continued in a nnedial direction 

 in tiie intervortebral fissure {f.i.r.) of von Ebnkk to ([uite near the 



vi.c 





Fig. 2. 



th. = chorda dorsalis ; n.s. ~ nei-vus spinalis ; a.i.s. = arteria interprotovertebralis ; 

 m.c. = myocoel ; f.i.v. = intervertebral fissure. 



chorda. The scleromere is divided, as was described above, by 

 this intervertebral fissure into two halves, a cranial half and a 

 caudal half. In the cranial half we see the N. spinalis (n.s.), the 

 caudal iialf is represented striped in conformity with the fact that 

 it is as a rule considerably stronger tinged. Somewhere in this row 

 of sclcromeres, which encloses consequently the spinal part of the 

 skull and the immediately adjoining part of the vertebral column 

 at some period or other of the development the cranio-vertebral 

 interval will manifest itself. 



What is interesting for us at the occurrence of this interval is 

 not the question, where it will present itself, in this sen.se, as if it 

 were of importance for us, how many scleromeres will join the 

 cranium This problem remains here entirely out of consideration. 

 What we want to know of the interval is, whether it coincides 



