E. C. PUNNETT 
347 
EXPLANATION OF PLATE. 
Fig. 1, a — c. Showing the different positions of the anterior spine with regard to the vertebral 
cartilages. The numbers refer to the whole vertebra to which the spine is regarded as belonging. 
6d = basidorsal cartilage, id = interdorsal cartilage, la is taken from No. 14:6, 16 from 147 and Ic from 
148 of the ? adults. 
Fig. 2. Caudal end of embryo No. 139 x 8. The no. 30 indicates the 30th half vertebra. 
Fig. 3. Caudal end of embryo No. 85 x 8. The 33rd and 34th half vertebrae are not separated as 
regards their centra. 
Fig. 4. Longitudinal section through occipital region of skull and first few vertebrae. From ? adult 
No. 53. The spinal cord and brain have been removed. 
Fig. 5. Preparation similar to Fig. 4. From ? adult No. 45. There is less condensation at the 
base of the skull than in the preceding figure. 
Fig. 6, a — c. Longitudinal sections through the junction of half and whole vertebrae. The last 
whole vertebra is in each case numbered, la is taken from ? adult No. 64, 16 from ? adult No. 26, 
and Ic from ? adult No. 34. 
Fig. 7. View of vertebral column of a single specimen after cleaning. In this specimen there are 42 
whole vertebrae and 43 half vertebrae. The anterior spine is carried by vertebra 16, the posterior by 
vertebra 40. The dorsal spines in the caudal region have been omitted. 
Note to Appendix, Tables 11- — 12. 
These two tables present the raw data for adults of both sexes. Of the abbreviations used 
g. p. n. signifies the 1st girdle-piercing nerve, p. g. n. the post-girdle nerves, and coll. n. the 
number of nerves which take part in the formation of the nervus collector. Length w. v. and 
length h. v. denote the length of the series of whole and half vertebrae respectively and the 
values given are expressed in centimetres. When two numbers are given for the g. [>. n. in a 
bracket as in individuals 9 — 11 of Table 11 it signifies that there are 2 g. p. n. and that both 
right and left sides are similar. 
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