COMMON STARFISH. 313 



the right of c is seen one of the interradial septa to which the ducts 



of the generative coeca on either side are attached. 

 d\. Ampullae of ambulacral feet of radius IV. 

 di. Ampullae of radius V. 



e. Subcentrally placed anus. 



f. Origin of extensor muscle of radius I from inner surface of centre 



of dorsal integument. It is by the action of this muscle that the 

 distal extremity of the rays and the eyes they carry, have their 

 ordinary up-turned direction, as shown in this figure, given to them, 

 /i. Distal termination of extensor muscle of radius V. 



g. Madreporic canal and plate displaced backwards into the interradial 



space of the bivium, opposite to which it is placed in the natural 



position of the parts. 

 h. First ambulacral ampulla, 

 /i and/ 2. Reproductive glands of radius III, consisting of multiramified 



coeca appended to a single efferent duct, as in many but not all 



proctuchous Asteroidea, and in Ctenodiscus amongst the aproctous. 

 y 3. Point of attachment of efferent generative duct of right generative 



gland of radius V to interradial septum, which is formed by the 



prolongation inwards of the integument containing a number of 



small flat ossicles. 

 k i and k 2. Median ends of ambulacral ossicles forming the vertebral 



ridge with median furrow. 



