TROCHUS. 305 
It appears, if there be no error, an unaccountable condition, 
that all pectinibranchous animals having spiral circular oper- 
cula should be hermaphrodites, whilst those of the same 
respiratory structure, with opercula of every other shape, 
should be bisexuals. It would be a loss of time to attempt to 
explain what is inexplicable; we refer to, and must rest on, 
the anatomical details at the conclusion of the descriptive 
notes. 
* Conical, and not umbilicated. 
TROCHUS, Linneus. 
T. GRaNuLatus, Born. 
T. granulatus, Brit. Moll. ii. p. 499, pl. 67. f.7, and pl. 68. f. 3; (ani- 
mal) pl. D.D. f. 4. 
Animal inhabiting a conical spiral shell of white or pink 
colour, furnished with close-set circular moniliform strive. 
Mantle plain and even with the aperture. The head is a 
long, thick, smooth elongated muzzle, yellowish-white, marked 
with fine longitudinal pale red-brown lines and points, and at 
an eighth of an inch from the termination clothed with an 
excessively close-set, very fine white fringe, that falls over the 
anterior part of the head like hair, which is scarcely visible 
without being floated, giving the buccal disk the appearance 
of being deeply sunken ; it is striated with brown lines, verti- 
cally cloven, and contains a pair of oval greenish-white horny 
lamin, supported by fleshy plates, between which the very 
short lingual riband passes to the cesophagus. The tentacula 
are long, tapering, pointed, rather flat, and marked above with 
a longitudinal central brown line, yellow beneath; the eyes 
are on short distinct external offsets, the cornea bemg dark 
blue with a black pupil. The head-lobes are very small, 
lateral, close to the inner angles of the tentacula, and are 
mere partially-cloven white fillets; the neck-lappets form two 
large, pendent, sinuated, slightly scalloped, yellowish-white 
membranes, of similar figure, not differing as in some species. 
The foot is very large, extending beyond each end of the shell, 
anteriorly subtruncate, dilated at the external angles, and 
tapermg to a lanceolate posterior extremity, which is marked 
x 
