ON SOME PLYMOUTH HOLOTHURIANS. 



219 



The number of gonadial tubes was also counted in a few small specimens 

 of C. saxicola and in one small immature specimen of C. normani. In 

 specimens of the former of 3-8, 3-1, and 2-8 cms. in length, there were 

 respectively 8, 4, and 6 small tubes, while in the specimens of C. normani 

 of 3-3 cms. in length there were 199 tiny tubes. 



It is thus evident that there is a marked difference between C. saxicola 

 and C. normani in the characters of the shape and number of the gonadial 

 tubes. 



Fig. 5. — External view of the calcareous collar of G. normani, drawn from a glycerine 

 preparation after separating the ventral piece from the adjacent right radial piece 

 (X V»). 



CHARACTERS OF THE CALCAREOUS COLLAR OF 

 C. SAXICOLA AND C. NORMANI. 



The calcareous collars of both C. saxicola and C. normani consist alike 

 of 5 radial alternating with 5 interradial pieces, and in both forms three of 

 the ventral pieces, one radial and two interradials, are partially fused 

 together. (See Figs. 4 and 5.) There is, however, a general difference 

 in the relative stoutness of the collars in the two species, and some 

 differences in the shapes and mode of connexion of the parts. 



