PLATE 36. 



Reconstruction of posterior end of Chaetoderma argentea. 



Same of Chaetoderma attenuata. 



Advanced stage in spicule development, the matrix cells retaining their attachment to 

 the spine. Proneomenia hawaiiensis. X 555. 



Somewhat earlier stage than fig. 3. X 5.55. 



Completion of spicule development and commencement of shifting of matrix cells. X 555. 



Reconstruction of anterior end of Strophomenia triangularis. 



Early stage in development of spine in Proneomenia hawaiiensis. X 555. 



Hypodermis in Limifossor fratula. X 255. 



Posterior end of Alexandromenia agassizi. X 3. 



Papilla and outlet of salivary gland in A. agassizi. 



Very early stage in development of spine in Proneomenia hawaiiensis. X 555. 



Blood corpuscles of Strophomenia scandens. X 450. 



Same of Chaetoderma hawaiiensis. X 450. 



Same of Lophomenia spiralis. X 450. 



Spines of Strophomenia triangularis. X 150. 



Same of Strophomenia spinosa. X 205. 



Same of Strophomenia ophidiana. X 205. 



Completed development of radially directed spine of Proneomenia hawaiiensis; and 

 developing papilla. X 555. 



Fig. 19. Base of gill plates and attached gland cells (gc), Alexandromenia agassizi; nc, nerve. 



