110 K. J. Bush — Marine Gastropods referred to 



There seems to be considerable doubt in regard to T. nivea, 

 the other species described by Adams under this genus. In 

 P. Z. S., for 1850, he described under Cyclostrema, as {Turbo) 

 nivea Chemnitz, a species in the Cumings collection, which he stated 

 is the Delphinula Icevis oi Kiener; and in 1863, under Ihbiola he 

 described as (Turbo) nivea Chemn., a rare species which is not in the 

 Cumings collection, nor in any other, and is not D. laevis Kiener, 

 and " agrees exactly with the original description and figures of 

 Chemnitz." The nivea of Adams is described as having " the last 

 whorl large, dilated in front, round at the periphery bordering upon 

 or spreading out at the peritreme; aperture oblique, sub-circular, 

 angulated below," etc., etc. 



As it is impossible for any one to settle such confusion without a 

 careful study of the specimens, I use cornuella as the type of the 

 genus. 



Fischer used Tubiola as a section under Cyclostrema, but unfortu- 

 nately cited serpuloides (Montagu) as an example, and did not men- 

 tion either of the above species. 



The relation of the genus to Morcliia or possibly to Skenea can 

 only be definitely settled by the comparison of authentic types. 



Circulus Jeffreys, 1865. Type, G. Duminyi Requien = striatus Wood = striatus 

 Philippi. Sicily, The Crag, and Ireland. 



Plate XXIII. fig. 11. 



"Very small, circular, nearly flat-spired with exceedingly wide 

 and open umbilicus." 



" Operculum circular with about a dozen volutions which wind 

 spirally and gradually and converge to the centre." 



Type, C Duminyi (R.) Jeffreys. 



Described in B. C, iii, p. 315, and poorly figured v, pi. 62, f. 5. 



In 1883 (P. Z. S., p. 94), Jeffreys I'edefined the genus as follows : 



" Animal not known." 



" Shell coin-shaped or forming a circular, compressed disk, slightly 

 nacreous or pearly ; mouth quadrangular with a continuous peri- 

 stome ; umbilicus very wide ; operculum multispiral, as in other 

 genera of TrochidjB." 



Specimens of Duminyi from both Naples and France, in the U. S. 

 National Museum, have been loaned me through the courtesy of Dr. 

 Dall. The above statement of their being slightly nacreous or 

 pearly is very misleading and quite erroneous. The interior is very 



