30 



K. MiTSTKria : s'itdies on 



Specimens uxjiinined :- 



Description: — "Body elongate, equally rounded at each ex- 

 tremity, llattened. ISIouth ventral, with twenty yellow tentacles. 

 Aims subdorsal. Dorsal surface with conical processes, few in 

 number, of equal size, the largest me;isuring 5 to 10 mm. in length; 

 those processes which attain a greater size are thinly placed on or 

 in the neighbourhood of the two dorsal ambulacra, while the 

 smaller are to be found partly in wvy limited numbers scatteri'd 

 among the larger, partly more crowded, forming it simple row 

 along the sides of the body and round its anterior extremity. The 

 pedicels probably form a double row along eacli lateral ventral 

 ambulacrum, but on the odd ambulacrum, marked out l)y a deep 

 furrow, I could not convince myself of the i)re,sence of any such 

 appendages. The calcareous ring is very reduced, in the larger 

 specimens absent. Two genital bundles, one on each side of the 

 dorsal mesentery. A single Polian vesicle and madreporic canal. 

 Body-wall thick, strengthened by C-shaped l)odics and tables. In 

 some parts of the body the s^jires grow much larger, and possess 

 much more numerous transverse beams : in others all the tables 

 become very robust, with a greater numl)er of holes in the highly 

 dilated ends of the arms, and with the spire more irregularly 

 developed and highly spinous. As a I'ule, the four I'ods which 

 constitute the spire are almost parallel and jirovided with spires. 



