41 



form of a cone, the two cones being- connected in each 

 vertebra by the pin-hole notochordal canal (Canalis 

 dicentralis). As all these spaces are occupied by the 

 " remains " of the notochord, the latter is absolutely con- 

 tinuous from one end of the column to the other. 



The following description is based mostly on a large 

 specimen of an extreme length of 52cm. In this animal 

 the neural spines were inclined as follows : 1, slightly 

 forwards ; 2, 3, 4, 5, almost upright', 6, slightly forwards; 

 7-13, all slightly curved (with the convexity forwards) 

 and project more or less forwards ; 14, largest spine (first 

 caudal) and projects slightly backwards ; from 1-14 the 

 neural spines increase in length; behind 14 ihey all 

 incline backwards, the inclination becoming more and 

 more marked as the extremity of the tail is reached, 

 and they also decrease in length. With regard to the 

 haemal spines (of which the anterior ones are very much 

 longer than the corresponding neurals), the first 3 incline 

 slightly forwards ; 4 is vertical ; 5 looks backwards, and so 

 do the remainder, the tendency becoming gradually 

 exaggerated behind, and at the same time the spines 

 becoming shorter until they are about the same length as 

 the neural spines. In the average specimen the posterior 

 haemals are slightly longer than the neurals (cp. 

 fig. 19). 



In the posterior third of the body the vertebral 

 column is situated about half way between its dorsal and 

 ventral edges. In front of this region, partly owing to 

 the slight upward curve of the column, but principally 

 owing to the increased length of the haemal over the 

 neural spines, the column is situated markedly nearer the 

 dorsal than the ventral edge. In the anterior third it 

 begins to bend down again slightly, and this is especially 

 noticeable in the first 4 or 5 vertebrae, the result being 



