Specimens of Cephalodiscus densus. 



437 



some of the tubes tliere has been a cessation and subsequent 

 resumption of growth, for the more terminal part.s are paler 

 and more transparent than the rest, with a sharp line of 

 demarcation between the two. 



In the ' Terra Nova ' material of Cephalodiscus densus some 

 groups of tubes were found to be flanged externally (i6, p. 41, 



d 



Cephalodiscus densus from Kerguelen Island. 

 Upper ends of coencecial tubes, about x 6. 



and pi. V. fig. 6), and an explanation of the origin of the 

 flange may be afforded by the occurrence of infundibuliform 

 ostia such as here shown in the text-fig., d. If the growth of 

 such a tube were resumed, and the new part were narrow, like 

 that shown in the text-fig., e, the margin of the funnel would 



