TROCHUS. 315 
as the sole, though diminished to be within its margins; it 
carries near the extremity the circular, corneous, moderately 
close-set, spiral operculum of 6-8 turns, and on each side, at 
equal distances, three, not very long nor slender, flattish ten- 
tacular filaments issuing from tubercles of the same elegant 
structure as the capitular ones; these are not vibrated with 
the usual activity of the tribe, but the curved auricles of 
the foot may be said to be “lete vibrantes.” The verge 
springs under the right tentaculum; it is flat, poimted, and 
hes horizontally, nearly extending to outside the aperture, 
not reflected in the branchial vault. The canal of depuration 
is visible at the right side just above the first vibraculum ; it 
is a short pendent shoot or cylinder. 
This animal inhabits the coralline zone in fifteen fathoms 
water, five miles off Budleigh Salterton ; it is active, marches 
with quickness, not at all shy, and gave me good opportunities 
of observing its peculiarities. 
It thus appears that the principal differences between this 
species and its congeners are the mere specialties of the want 
of distinct eye-pedicles, and the long linear curved auricles of 
the foot. Axis, diameter ,/, uncie. 
This very important discovery of a desideratum that has 
hitherto escaped detection, proves that the animal is nearly a 
strict Trochus, which does not in the specialties show a greater 
departure from the Trochidan type than is often seen amongst 
the most classic species. This fact determines the fate of the 
genus Skenea: its provisional members, the S. Cutleriana and 
S. nitens of Philippi, called by some authors “ Trochus pu- 
sillus,’ are in all probability Trochi; but I will not venture 
to say as much of S. nitidissima. The S. levis is scarcely a 
variety of our present species. 
T. CurLertanvs, Clark. 
? Skenea Cutleriana, Brit. Moll. in. p. 164, pl. 88. f. 3, 4; iv. p. 270, 
pl. 132. f. 4, 5. | 
? S. costulata, Brit. Moll. iii. p. 167; iv. p. 271. pl. 182. f. 1, 2,3. 
T. testa suborbiculari, albida, aliquantulum producta, anfractibus 
tribus spiraliter exaratis; striis subtilibus, undatis, transversis, 
