466 THE VOYAGE OF H.M.S. CHALLENGER. 



3. Siliquaria, Bruguiere, 1792. 



Siliquaria {Tenagodus) bernardii, Morch. 



Tenagodus bernardii, Morch, Journ. de conch., 1860, vol. viii.'p. 368, and 1865, voL xiii. p. 23, 



pL iv. fig. 3. 

 Siliquaria bernardii, Reeve, Conch. Icon., vol. xx. pi. iv. fig. 9. 



May or April 1873. North Atlantic. Deep water. 

 Habitat. — Senegal (Reeve). 



Family Turritellid.e, Gray, 1857. 

 Genus Turritella, Lam., 1799. 



The genus Turritella is a group well defined, as regards the shell, the animal, and the operculum ; 

 nor is it unmanageably large. There is therefore no primd facie reason for breaking it up as Gray has 

 done ; and his destructive process has not justified itself in the characters of the genera he proposed, 

 which are neither strongly marked nor constant. The consequence is that the lists of species arranged 

 under Turritella (with subgen. Haustator), Torcula, and Zaria are arbitrary in the extreme ; and these 

 divisions only cause confusion. 



There are two remarkable features of Turritella which do not seem to have been noticed. The 

 first is the system of microscopic spirals which covers the entire shell, and which I have found on 

 every even fairly preserved specimen which I have examined. The second is the presence of an 

 epidermis. This' is very distinctly recognisable in Turritella carlottce and in Turritella austrina, and 

 somewhat doubtfully in Turritella admirabilis. It is filmy, calcareous, and in drying seems to con- 

 tract, so as to rise off the surface of the shell in the furrows, remaining attached only to the tops of 

 the spirals and in the suture. It also splits in the lines of growth. All this renders it of course 

 very caducous ; and, as Mr E. A. Smith remarks, " the fact of all Turritellas appearing to be devoid of 

 an epidermis is quite comprehensible, seeing how excessively thin it is in this instance" (i.e., of Turritella 

 carlottce, which I had sent to him for examination). Hardly sufficient importance seems generally 

 given to the sinuation of the outer lip, which is a feature quite as distinctly marked as in Pleurotoma. 



Species. 



1. Turritella bicingulata, Lam. 10. Turritella atistrina, Wats. 



2. Turritella cingulif era, Sow. 11. Turritella deliciosa, Wats. 



3. Turritella exoleta (Linne). 12. Turritella adviirabilis, Wats. 



4. Turritella fascialis, Menke. 1 3. Turritella lamellosa, Wats. 



5. Turritella fastigiata, Adams and Reeve. 1 4. Turritella runcinata, Wats. 



6. Turritella lenysndensis, Krauss. 15. Turritella aceisa, Wats. 



7. Turritella rosea, Quoy and Gaimard. 16. Turritella carlottce, Wats. 



8. Turritella sinuata, Reeve. 17. Turritella philippensis, Wats. 



9. Turritella cordismei, Wats. 18. Turritella (Eglisia) tricarinata, Adams and Reeve. 



