Manchester Memoirs, Vol. xlii. (1898), No. 4. 27 



striation or sulcation is uniform, and close. At the bottom 

 of each whorl, just above the sutures, the sulci are broader 

 and funiculate, and tessellated with red, the remainder of 

 the surface is sometimes flushed with red, and sometimes 

 quite plain. 



A good many examples, all alike in form, but differing 

 slightly in pattern, as described above. 



{duricastelliim, a stronghold.) 



OSTREA TOWXSENDI, Sp. nov. 

 (PI. 2, f. 14.) 



O. testa suborbiculari, albida, dorsaliter rufo-suffiisa, 

 probabiliter per lobos valvce inferioins adhcerente, valva 

 siiperiore inultiplicata, costis raniosis, apud medium, prcEcipiie 

 dorsaliter, elevata, siiperficie delicate longitudinaliter sericata, 

 margi7ie7n ad ventralem lamellata plicis albidis, qiiindecim 

 ad septenidecim, divaricatis, plicis variis, acute angulatis, 

 cardine magno, supei'ficie interna albo-ocJiracea. 



Alt. 275, lat 3 unc. 



Hab. On the Telegraph Cable, entrance to Persian 

 Gulf 



A few specimens, which, when cleared of nullipores 

 and other growths, present a beautiful shell surface. We 

 could almost give it the palm in a genus which, uncouth 

 as are many of its members, yet in some few instances 

 almost rivals the Spondyli. The present species which, 

 rightly, is to bear the name of its discoverer, Mr. F. W. 

 Townsend, is suborbicular in shape, white, many plaited 

 round the ventral margin, the plaits being acute-angled. 

 Transverse lamellae are seen above the plaits, the rest of the 

 surface being beautifully longitudinally sericeous and 

 shagreeiied ; dorsally there is a suffusion of red-brown, 

 the depressions between the branching ribs being darker. 

 The hinge is large, inner surface yellowish white. 



