DEVELOPMENT OF CUCUMARIA. 641 



PliTE II. 



Fig. 9. C. normani. Graphic reconstruction (by superposition of camera lucida 

 outlines) of a larva on the middle of the third day, viewed from the left 

 side. The reconstruction was arrested at the median plane in the case 

 of the body-wall, the gut, the ventral horn of the posterior coeloin, and 

 in the neighbourhood of the madreporic pore, so that these are seen in 

 section. The hydrocoel is seen in its oriter aspect — I. e. its concavity is 

 towards the right. The large anterior lobe is the mid- ventral canal. 



10. C. saxicola. Coronal section of a fourth-day larva to show the relation of 

 the rudiments of the primary podia to the mid- ventral canal. Note that 

 the radial canal is solid at this stage. 



11-14. C. saxicola. Four transverse sections through a fourth-day larva to 

 show the relation of tentacles to radial canals. Figs. 11-13 are of con- 

 secutive sections ; one section is missed between 13 and 14. The order 

 of the sections is from the posterior to the anterior end of the larva. 



15. C. saxicola. Coronal section through the stone-canal of the same larva 

 as fig. 10. Leitz 2 mm. apochr. obj., comp. oc. 6. 



