DENTALIUM-ANTALIS. 39 



Stoliczka iu 1868 restricts Antalis to the species of the type of 

 D. vulgare, in which there is a supplemental tube at the apex, sep- 

 arating it generically from Entalis Gray. Tryon and Fischer fol- 

 low Stoliczka's definition of Antalis or Antale and Entalis. 



Finally, Newton and Harris in 1894 finding Entalis Gray pre- 

 occupied by Sowerby (but not by Defrance, as they allege) substi- 

 tute Entaliopsis for the group. 



It appears, therefore, that Entalis Gray, Entaliopsis Newton & 

 Harris and Antalis Ads. are absolutely equivalent, being based 

 upon the same species as type. 



There is another chapter of this history, in which the genesis of 

 "Entale" (Defrance's Gallic vernacular for Entalitnn) is dealt 

 with, the vicissitudes of its career related, with at last its final trans- 

 formation into " Entalis." The details of this melancholy tale may 

 be found by the curious in the section of this volume treating of 

 Pyrgopolon. 



Group of D. entalis. 



Shell moderately or very solid, circular in section ; white or red- 

 dish toward the apex ; near the apex always sculptured with longi- 

 tudinal riblets or striee, at least in the young, but frequently the 

 greater part in adults is smooth, with growth-lines only. Apex 

 typically with a slightly projecting " sheath " interrupted by a small 

 V-shaped notch on or near the convex side. 



North Atlantic, Mediterranean and North Pacific in distribution, 

 from shallow water to the greatest depths reached. 



In many species of this group the inner layer of the shell is of 

 more porcellanous, firmer texture than the outer, and by the pro- 

 gressive erosion of the smaller end with growth this layer projects 

 slightly as a sort of narrow, elevated rim around the apical orifice, 

 interrupted on one side by the notch, as shown in fig. 25 of plate 8. 

 This condition, while usual in some species and likely to occur in all 

 of the group, is by no means invariable in any of them. In some 

 forms the inner layer thus exposed by erosion, may form a longer 

 tube, as in the young specimen of D. agile which JeflTreys called D. 

 vagina. The same structure occurs iu D. agassizi and many other 

 forms. This tube is not homologous with the apical tube of D. 

 vulgare (which is probably more allied to the novemcostatum group), 

 or of D. filum, etc. 



