ECHINODERMA TA 



239 



ciliated pores which traverse the integument. This system 

 represents the stone canal of Asterids. In one ■ species of 



Fia. 141. — A longitudinal section through the plane of the mouth and anus of 

 Pentacrinus decorus, Wyv. Th. After Carpenter. 



1. Mouth. 



2. Alimentary canal. 



3. Anus. 



4. On the left, the axial cord of the 



ray ; on the right, extensions of 

 nerves from the axial cord into 

 the plated perisome of the ventral 

 side. 4i, ambulacral nerve. The 

 central nervous mass is shown at 

 4, near the basal plate. 



5. Basal plate. 



6i, 62, 63. First, second, and third radial 



plates. 

 7i, Ta. First and second distichal 



(brachial) plates. 



8. The more or less calcified connective 



tissue in the body-cavity. 



9. Central vascular axis of stem. 



10. A cirrhus. 



11. Genital rhachis. 



12. Ligament between the ray joints. 



13. Radial water-vessel. 



The black plexus of blood-vessels in the centre of the figure is the plexiform gland, 

 containing the genital stolon. 



Ehizocrinus there is one canal and one pore in each interradius, 

 but the number is much increased in other Crinoids. 



The five genital strands are continuous with a central 

 genital stolon, which here, as in Asterids, has been mistaken for 

 a heart by German authors. Around this stolon are numerous 

 vessels, which in the central capsule of the dorsal nervous 



