CALLIOSTOMA-EUTROCHUS. 411 



no sign of a notch or sulcus in the lines of growth. The dentition 

 forms a combination so far not recorded among the Trochidse, but 

 which will perhaps seem less singular when more species have been 

 examined. The radula is quite minute and difficult to examine ; 

 when only the cusps of the central and lateral teeth were in the 

 field of the microscope, they were so slender and elongated as to 

 suggest little tails, and the symmetrical notching gave them almost 

 a jointed appearance. The shell is very pretty, and recalls Basilissa 

 in its general appearance. (Da//.) 



(Section Dentistyla Dall, 1889.) 



C. ASPERRIMUM Dall. 



Shell conical, yellowish white, turreted, higher than wide; whorls 

 five to seven, the last forming half the height of the shell ; base 

 rounded, umbilicus small, partly covered by the reflexed lip, trans- 

 versely striate, with one longitudinal thread close to the bounding 

 nodulated strong carinal rib ; upper whorls with two strong longitu- 

 dinal ribs, the lower of which forms the carina of the last whorl ; 

 near the beginning of the latter a single less conspicuous thread is 

 intercalated between these two ; the carina is above the middle of the 

 last whorl, and between it and the bounding rib of the umbilicus are 

 four strong simple revolving threads, not nodulated, between which 

 near the mouth, intercalary, weaker threads begin to appear. Sut- 

 ure distinct, compact not channelled, except by projection of the 

 ribs above and below it which give the shell a turreted appearance. 

 Lip thin or slightly thickened, denticulated on the edge by the rib 

 ends ; pillar little thickened, its base apparently toothed by the ends 

 of the umbilical threads (these denticulations are probably missing 

 in the perfect adult) ; mouth slightly oblique, not produced below ; 

 transverse sculpture consisting of threads following the lines of 

 growth, rising into lamellae between the ribs, and in passing over 

 them (except the basal ones) forming squarish projections, cutting 

 the ribs obliquely. Nucleus smooth, polished, the remainder dull 

 white, with no visible nacre. (Dall.) Alt. 7?, diam. 6 mill. 



Off Martinique and Barbados, 100-220 fms. 



Var. DENTIFERUM Dall. PL 60, figs. 10, 11. 



Sculpture more strongly and exclusively nodulous ; a strong blunt 

 tooth on the columella just within the aperture and above the base. 

 Outer lip lirate within. Alt. 7 2, diam. 6 mill. (Dall.) 



Off Barbados. 



