Cyclostrema^ Adeorbis, Vitrinella, and related genera. 1 1 3 



typical form would place the genus in close relation to Lissospira or 

 possibly Leptoyyra, although no epidermis is mentioned ; but the 

 form of the aperture of the variety expansa (figs, \1a-b) is very 

 different and much closer to that of his Adeorbis fragilis (figs. 19a-c), 

 the generic relation of which is very doubtful. 



Fischer placed the genus w^ith the Adeorbidse with a mark of 

 doubt, while Tryon (Manual, x, p. 13) placed it as a synonym of 

 Archytma de Costa, 1869, which is said by him to have the same type, 

 A. delicatum of Philippi (p. 87). I have been unable to consult the 

 Ann. Mus. Naples, iii, in which the latter genus is described. 

 Fischer placed this with Solarium with a mark of doubt, but gave 

 A. catenidata de Costa for an example. 



Tharsiella' Bush, 1897. Type, T. romeliensis (Seguenza). Pliocene. Calabria and 

 Sicily. Mediterranean, Bay of Biscay, etc., in 108-1093 fathoms. 



" Shell globular, solid and glossy ; peristome circular and continu- 

 ous, but attached to the pillar on that side : base closed by a pad or 

 thick testaceous layer in the adult, perforated in the young : opercu- 

 lum chitinous or horny, and multispiral." 



"This genus differs from Cyclostrema (i. e. Lissospira) in the 

 peristome being, although continuous, not free or detached from the 

 rest of the shell, and in the umbilicus being closed instead of open in 

 the adult," etc., etc. P. Z. S., p. 92, pi. xix, fig. 7, March, 1883. 



Fischer placed this as a subgenus under his Cyclostrema, but Mr. 

 Dall (Bull. Mus. Comp. Zool., xviii, pp. 361-3, 1889) thought it 

 might prove to be a sjnionym of, or at most, a feebly characterized 

 section of Ethalia ; but his conception of that genus is in its most 

 extended sense. See p. 116. Moreover, Mr. Jeffreys may have had 

 two forms under the name romettensis, for his figure 7 certainly more 

 closely resembles a Lissospira than an Ethalia, so that I place the 

 genus with the Vitrinellidte until some knowledge of the animal and 

 odontophore can definitely decide its position. 



The specimen (No. 38244) from off Cape Hatteras, N. C, station 

 2115, in 843 fathoms, described by Professor Verrill (these Trans., 

 vi, p. 201) as Tharsissp., is unquestionably a small species of Natica. 

 The aperture is broad- ovate, somewhat produced ; the peritreme is 

 modified on the body-whorl into a rather conspicuous glaze, and the 

 columellar margin is thickened and reflected over the umbilical chink, 

 with a slight median expansion. 



Iharsis Jeffreys, 1883, non Giebel, 1847 (Pisces) ; nee Tharsus Leconte, 1862 (Insecta.) 

 Trans. Conn. Acad., A^ol. X. * July, 1897. 



