242 BULLETIN: MUSEUM OF COMPAEATIVE ZOOLOGY. 



iguored in the index to his volume. It is uncertain which use of Cylindrella 

 was prior, Swaiusou's or PfeifFer's; the latter having also used the name (for 

 laudshells of the genus Urocoptis Beck) in 1840. The presumption, however, is 

 in PfeifFer's favor, in comparison with Swaiusou. It would be a pity to resurrect 

 a name so well known in so unfamiliar a connection. Cylichnus Burmcister is a 

 barbarism, and cannot be derived by any recognized rule of orthography from the 

 Greek KvKiyvrj, frqm which we might obtain Cylichnes or Cylichnium, as well as 

 Cylichna. The latter might thus be plausibly held until it be shown that Cylich- 

 nus is a masculine form of it. I do not like to use Mnestia for the genus, 

 thinking it highly improbable that the colored species for wliich that name was 

 proposed are identical with the group typified by C- cylindracea Pennant. The 

 next name in order of date is Cylicliuella Gabb, the shell of which differs from 

 Cylichna by having two distinct plaits on the pillar instead of one, and since this 

 has been recognized by Gabb, Pilsbry, and others as a distinction of rank not 

 greater than subgeueric Cylichnella will become the generic name with the species 

 formerly grouped under Cylichna now forming a subgenus with the name of 

 BulUnella Newton. It is of course understood that with the general knowledge 

 of the anatomy some revision will undoubtedly be called for. 

 The genus may be subdivided as follows : 



A. Shell Unicolorate, Ctlindric. 



Cylichnella. Gabb, s. s., type C, bidentata Orb. Pillar with two distinct 

 plaits. 



BuLLiNELLA. Ncwton, type C. cylindracea Pennant. Pillar with a single plait. 



CvLicHNiCM Dall, nov., type Utriculus domitus Ball. Pillar simple, aperture 

 ample in front. 



B. Shell Versicolored, Scbovatb. 



Mnestia H. and A. Adams, type, C marmorata Adams. 



Cylichnella (Bxillinella) inca Dall, n. ep. 



Plate 11, figure 3. 



Shell small, white, with a pale yellowish periostracum (mostly eroded), the 

 aperture as long as the shell ; spire entirely and deeply immersed, leaving only a 

 small deep cylindrical perforation at the apex ; summit of the whorls rather evenly 

 rounded, except where slightly indented by tlie more pronounced incremental 

 irregularities ; sides nearly parallel, the posterior end, if anytliing, with a slightly 

 greater diameter ; surface smooth (where not eroded) except for lines of growth ; 

 middle of the shell a trifle constricted ; body with a light wash of callus ; outer 

 lip thin, sharp; pillar a little twisted with a faint trace of a revolving ridge upon 

 it; anterior end rounded. Lon., G; max. diam., 2.5. mm. 



U. S. S. " Albatross," station 3392, olT the Gulf of Panama, in 1270 fathoms, 

 hard bottom, temperature 30°. 4 N. U. S. Nat. Mas., 123,080. 



