TURRITELLA. 195 



Genus MATHILDA, Semper, 1865. 



Shell turrieulatecl, rather solid, apex lieterostrophe, abruptly 

 turned from left to right ; whorls in the typical species trans- 

 versely cingulated and reticulated, longitudinally striated ; aper- 

 ture entire, subrotund, base sometimes subeffuse ; lip acute, 

 columella smooth. Operculum corneous, rather solid, multi- 

 spiral, the external face concave, nucleus central. 



Animal with verj' long thread-like, divergent tentacles, with 

 rather large e^-es on prominences upon their exterior side, about 

 a quarter of their length from the base ; foot large, cut out in 

 front, obtuse behind ; operculigerous lobe having a row of cilia 

 in constant movement. 



Seas of Europe, China, Australia, Strait of Magellayx. 



There are about thirty tertiary and a few secondary species. 



" Mathilda," writes Dr. Fischer, " has the shell of Turritella, 

 with the heterostrophe embryonic whorls of P^-ramidella ; the 

 exterior form of the animal, the position of the eyes, and the 

 structure of the operculum, relate it to the former," On the 

 other hand, Monterosato finds in it affinities with Solarium, and 

 Jeffreys places it in the Pyramidellidse. The radula is unfortu- 

 nately-unknown. 



Subgenus Gegania, Jefrre3s, 1884. 

 Shell small, conic, reticulated, imperforate, the nucleus glob- 

 ular and twisted, not spiral and not sinistral. G. PiNGris, Jeffr. 



Coast of Portugal (abj^ssal). 

 Differs from Mathilda in its short spire and nonheterostrophe 

 apex. 



-K 



Genus TURRITELLA , Lam., 1799. 

 Section Tukritella (typical). 

 T. TEREBRA, Linn. PL .59, figs. .32, 33. 



"Whorls convex, each with about 6 revolving ridges and inter- 

 mediate close striae, suture deep ; j-ellowish brown to chestnut- 

 color. Length, 5-8 inches. 



Singapore, Java, Philippines. 



T. Archimedis, Dillw^-n, is a synonym, and T. spectrum, Reeve 



(fig. 33), is at most a variety, developing more numerous ridges. 



