MODIOLARIA. 



191 



Modiolaria nigra, LovJ;n, Ind. Moll. Scand. 33. — Morch, Prod. Moll. Groenl. 21.— 



MiDDENU. Malac. Ross. 17. 

 Mi/ti/us pectinitlus, Stimcson, Shells of New England, 11 (1851). 

 Modiolaria siriatula, Beck, in Gaim. Voy. in Isl. pi. 17, tigs. o-f. 

 Modiolaria discors, Middesd. Malac. Ross. iii. 15, pi. 12, tigs. 11, 12 (young). 



Shell small, thin, long-ovate, largest behind, slightly produced 

 at the posterior extremity ; basal edge less curved than 

 the superior edge, which is moderately compressed ; 

 beaks prominent, pointed, directed forwards, scarcely 

 touching each other, placed unusually far from the an- 

 terior extremity ; a rather sharp ridge passes from the 

 beaks diagonally across the shell, but loses itself about half-way 

 across. Surface very beautifully sculj)tured with a network of very 

 minute, crowded lines of growth, and very numerous, fine, indented 

 radiating lines or ridges, which are obsolete aloug two thirds of the 

 base, and most conspicuous behind, where a very fine line divides 

 into two each ridge, going to the extreme posteri(jr portion ; while 

 above these, on the compressed portion, a beautiful lace-work of hex- 

 agonal indentations is formed. The portion in front of the beaks 

 is conspicuously radiated. Epidermis a rusty brown, with shades of 

 olive, glossy ; interior livid, with a pearly or silvery lustre, and with 

 minute, radiating lines ; cavity of the beaks large ; margin simple. 

 Length, seven tenths of an inch ; height, nine twentieths of an inch ; 

 breadth five twentieths of an inch. 



This new and beautiful shell was taken by dredging in the harbor 

 of Provincetown, by 



Colonel Totten, where ^'°- *^^- 



he obtained several 

 living specimens. 



It is allied to M. 

 discors and M. dis- 

 crepans l)y its outline, 

 and by the triangu- 

 lar portion across the 

 disk, nearly destitute 

 of radiating lines. But 

 it is more compressed 



than either of those shells, less inequilateral, and its sculpture far 

 more beautiful. The radiating lines seem all to have indentations 

 or punctures like the wing-covers of many large beetles (Carabi). 

 The honeycomb arrangement near the hinge-margin is very beauti- 

 ful. Dr. Loven has sent me the shell, from Sweden, as the true M. 



M. nigra. 



