BIVALVIA. 75 



21. Modiola Bartonensis, S. Wood. Tab. XIX, fig. 18. 



A small specimen of a Modiola, of which the figure above referred to is a repre- 

 sentation, has very recently come into Mr. Edwards's possession. It is not in a state of 

 preservation sufficient for full and fair description, and I have proposed the above name 

 provisionally. It appears to be covered entirely with large rays or costulae ; it is more 

 elongated than the fragment figured at fig. 5, Tab. X, and it has not the diversified rays 

 which ornament that shell. 



22. Modiola (?) crassistriata, Edwards, MS. Tab. XIX, fig. 16. 



Spec. Char. M. testa parvd, ovato-trigonuld, tenui, siphotii-regione depressiusculd, 

 radiatim costellatd aut crassistriata; costeltis vel striis rotundatis, dichotomis ; umbonibus 

 minimis, subterminalibus ; margine cardinali subrecto. 



Shell small, ovately triangular, thin ; siphonal region somewhat depressed, covered 

 with thick radiations or riblets, rounded and bifurcating; beaks small, nearly terminal; 

 dorsal area straight. 



Length, \ an inch. 



Locality. Bracklesham {Edwards). 



The specimen above described has recently been added to the cabinet of Mr. 

 Edwards, and I have considered it, as Mr. Edwards has done, a distinct species. It 

 differs from both of the previously described coarsely striated species, Jtabellula and 

 nodulifera, being much shorter than the former, with the striae or riblets somewhat finer; 

 and from the latter, with which it agrees in form, it differs in not having the nodules of 

 that species. Our present specimen is a pretty shell, and the rays with which it is 

 ornamented are rounded, the spaces between them rather narrow, or at least they are less 

 so than the rays themselves. The specimen adheres too closely to the matrix to permit of 

 a removal, and the interior is entirely hidden. It bears some resemblance to M. pectinata, 

 Lam. (Desh., ' Coq. foss. des Env. de Par.,' t. 1, p. 259, pi. 39, figs. 6—8), but our shell 

 is shorter, more angulated, with a comparatively longer dorsal area, and the striae are 

 coarser. 



The umbo in this is nearly terminal, with a very trifling projection of the pedal 

 region ; there is an uncertainty as to its correct admission into Modiola. 



11 



