66 DENTALIUM-FISSIDENTALIUM. 



e"". About 40 narrow riblets at apex, 

 becoming flattened and then ob- 

 solete ; slit 15 mill, long ; length 

 91 mill., 9 times the diam., 



ergasticum, p 74. 



e"". Light red ; length 82 mill., about 

 7 times the diam., 



milneedwardsi, p. 75. 



e'"". More cylindrical than candidum; 



length 78 mill., about 9 times the 



diam., complexum, p. 76. 



d". Many thread-like riblets separated by 



deeply cut intervals hardly narrower than 



the riblets. 



e. Solid, about 65 even, sharply and 

 deeply cut rounded equal threads, 

 with narrow grooves ; a slit ; length 

 about 80 mill., 9 times the diam., 



capillosum, p. 77. 



e'. About 40 flat-topped riblets, with 

 broad square furrows, 



paucicostatum, p. 78. 



e". Striation coarser, slit longer; length 



101 mill., about 7 k times the diam., 



magnificum, p. 78. 



e"'. Sculpture much as in capillosum ; 

 light reddish-gray; nearly straight; 

 length 95 mill., 10? times the 

 diam., scamnatum, p. 79. 



e"". About 80 thread-like riblets: a 

 notch or short slit ; length 90 

 mill., about 10 times the diam., 



profundorum, p. 79. 



c". Diam. contained 15 times in length ; 75 mill, 

 long ; finely ribbed, senivestitum, p. 75. 



II. Shell decidedly compressed, elliptical in section. 



a. Tawny, banded with brown ; very numerous unequal rib- 

 lets ; slit long and narrow, aperture oval ; length 72 mill., 

 6 times the diam., hungerfordi, p. 84. 



a'. White; about 16 angular, narrow, equal ribs, smaller ones 

 sparsely intercalated toward aperture ; intervals conspic- 

 uously transversely striated ; a long slit; length 51 mill., 

 12-13 times the diam., clathratum, p. 84. 



