PALASTERINA PROLE VA. 



225 



in Schuchertia, but the ossicles on the other side of the groove of the same arm as 

 figured show a thin ridge. 



MP 



M. 



Text-fig. 161.— Plan of the ossicles on the oral surface of Palasterina primxva. Ad., adambulacra 

 I.M., infero-marginal ; Ir., interradial plate ; M., madreporite ; M.P., mouth-angle plate. x 5. 



A very good view of the groove in the region of the mouth was obtained by 

 bending rubber casts of specimen k from the Sedgwick Museum while still 



Text-fig. 162. — Wash-drawing of an angle of the disc of Palasterina primxva (from Sedgwick Mus.). 

 Lettering as in Text-fig. 159. O , plate which corresponds in position with the odontophor of related 

 species, x 12. 



soft. The groove was thus forced open with but little distortion of the ossicles 

 (Text-fig. 138, p. 195). The mouth-angle plate is large. On its inner side it is 

 hollowed to lodge the first tube-foot. There is a distinct apophysis. Between the 

 apophysis and the oral surface of the plate runs the groove for the nerve-ring. 

 Behind the apophysis is the groove for the circular water-vascular ring. The hollow 



