216 A. E. Verrill — Molhtsca of the New England Coast. 



faint, or entirely disappear, though a part of them sometimes continue 

 to the anterior end, where they are distant and appear only as slightly 

 indented furrows or depressions; at about the posterior third the 

 number of grooves varies from twenty to forty. 



Color, usually grayish or slaty brown externally, bluish white 

 within; more perfectly grown and younger specimens arc white on 

 the anterior portion and only faintly bluish white within. 



Length of an average specimen, 82"""; diameter, at the anterior 

 end, 10'"™ ; at the posterior end, 2'"'". A more slender specimen is 

 75™"" long; diameter of the oral end, 9"""; of the posterior end 



1 . ( mm 



This species was taken in considerable numbers at numerous sta- 

 tions by the Albatross. Station 2050, in 1050 fathoms; 2052, in 1098 

 fathoms; 2077, in 1255 fathoms, numerous specimens, living and 

 dead (No. 34,904) ; 2083, in 959 fathoms, two specimens (No. 34,687) ; 

 2084, in 1290 fathoms, numerous specimens, living and dead (No. 

 34,911 and No. 34,688) ; 2102, in 1209 fathoms, one specimen; 2103, 

 in 1091 fathoms, numerous living specimens (No. 35,636) ; 2104, in 

 991 fathoms, two. dead ; and oft' Cape Hatteras, at station 2111, in 

 938 fathoms, numerous living specimens (No. 35,635); 2115, in 843 

 fathoms, one fine specimen (No. 35,645). 



This fine large species might readily be taken for a gigantic form 

 of Z>. striolatum or D. occidentale. It is, however, a much stouter 

 shell than either of these, of a thicker and firmer substance, and 

 with a relatively larger aperture. It differs also in the character of 

 the lono-titudinal sculpture. In D. occidentale the longitudinal 

 grooves are more numerous, broader and deeper, having more the 

 character of true furrows, with the intervening ridges mostly nar- 

 rower than the grooves, irom which they rise rather abruptly, with 

 well-defined border, while in the present form the grooves are merely 

 depressions in the general surface of the shell, with indefinite borders. 



In I), striolatum the longitudinal sculpture is almost obsolete, ex- 

 cept near the posterior end ; and such lines as exist have the same 

 character as in I), occidentale, though fainter, the two forms possibly 

 bein<>- only varieties of one species. The most perfect specimens of 

 J), soliduni have also two posterior notches, while in />. striolatum 

 there is usually a single notch on tlie dorsal side, but the character 

 of the posterior aperture seems to be variable in most of the species 

 of this group. 



