TURCICA-BASILISSA. 419 



stride. The base is strongly corded and deeply pitted. Of the only 

 two specimens known one is in the National Collection at South 

 Kensington, and the other is in that of Mr. MacAndrew. (Soicb.) 



Genus BASILISSA Watson, 1879. 



Basilissa WATSON, Jour. Linn. Soc. Loud., xiv, p. 593, April, 

 1879. Challenger Kept., Gasterop., p. 96. DALL, 'Blake' Gas- 

 teropoda, p. 383. 



Dr. Ball's diagnosis is as follows: Shell trochiform, umbilicate, 

 nacreous, sculptured. Pillar concave, its distal end projecting as a 

 strong tooth. Margin of the aperture concavely sinuate near the 

 suture and on the base. Peripheral margin produced, claw-like, 

 between the two shallow sinuations. A grooved or denticulate 

 callous in the adult on the body-whorl and within the margin of 

 the aperture. Aperture subrhomboidal. Operculum multispiral, 

 horny, with a circular callous on the inner central face, and a sub- 

 circular outline. 



The above amended diagnosis is rendered necessary by the dis- 

 covery of adult specimens among the Blake shells. It is probable 

 that most of the species in an adult condition conform to it. It 

 is conchologically related to Seguenzia, a transition form which is 

 indicated by such species as S. carinata, S. elegans, and S. trispinosa. 

 But the soft parts are as yet unknown. Should it be found how- 

 ever that some species do not exhibit the denticulation, etc., de- 

 scribed in B. costulata, and conform to the edentulous type indicated 

 in Watson's original description (and B. alta may prove to be of 

 this character), these would of course retain the original name of 

 Basilissa, while for the dentate forms the name of Ancistrobasis 

 might be used. (Dall.) 



Section BASILISSA s. s. 

 B. ALTA Watson. PI. 36, fig. 5. 



Shell an equilateral cone, flat-based, sharply angulated, small, 

 thin, delicately sculptured, nacreous under a thin, white calcareous 

 surface. Sculpture : there are longitudinals about 45, hair-like, 

 strongly sinuated, flexuous, for they advance markedly at the 

 periphery, where they are each ornamented by an elongated curved 

 tubercle, and on the base they again retreat so as to form a sinus. 

 On the earlier whorls these longitudinals are much more distinct 

 than on the later, and each starts from a little bead, which lies 



