DENTALIUM-FISSIDENTALIUM. 65 



at apex ; length 56-60 mill., 7-8 times 

 the diam. ; New Zealand, 

 opacuvi, p. 70 ; zelandicum, p. 70 ; pacifi- 

 cum, p. 70. 

 d". About 18 ribs at larger end, fewer poste- 

 riorly ; white, rapidly tapering, curved ; 

 length about 16 mill., about 6 times the 

 diara. ; New Zealand, huttoni, p. 71. 



. Tube less rapidly enlarging, the greatest diame- 

 ter contained 8 to 11 times in the length. 



d. 30-35 riblets on larger part of the shell ; 

 length about 8 times the diameter. 



e. Long, conic, finely tapering, white ; 

 30-35 unequal, rounded, close, 

 high ridges, finally obsolete except 

 for slight grooves ; a short slit ; 

 length 62 mill. ; aegeum, p. 69. 

 e'. About 30 unequal grooves near 

 large end, fewer posteriorly ; white, 

 solid, slightly curved ; length 60 

 mill. ; New Zealand, 



pacificum, p. 70. 

 d\ 40 or more flattened riblets separated by- 

 much narrower grooves. 



e. About 40 subequal riblets with 

 much narrower intervals ; toward! 

 apex alternately smaller ; length 

 90-133 mill,, 8-9 times the diam. ; 

 a deep slit or none, vernedei, p. 80. 

 e'. Solid, glossy, white or ashy-gray, 

 about 44-48 low, rather flattened 

 riblets, somevvhat fewer posteriorly, 

 parted by linear grooves, becoming 

 subobsolete toward aperture; length 

 74-88 mill., about 9 times the 

 diam., slit short, candidtmi, p. 72. 

 e". Similar, but 90 or more riblets, 

 continuous to aperture ; length 100 

 -110 mill., 8-10 times the diam., 

 meridionalis, p. 73. 



