308 TROCHID 2%. 
or T. Cutlerianus; the general colour is pale bistre, with a 
greater proportion of flake-white than im the “ tumidus,” and 
at the base of each tentacular sheath or tubercle there is a 
minute round brown-coloured spot. 
This species is far more rare than the “ tumidus,”’ and in- 
habits, with it, the coralline zone, at Exmouth. 
I have omitted to say that the neck-lappets are both plain, 
but of very unequal size; that of the right side is much the 
largest, and often rolls itself up like a branchial fold; they 
are both more or less speckled with flake-white spots; the 
margin of the foot, except the anterior line, is clothed with 
a short white setose fringe. There are two varieties, one with 
the volutions much more tumid ; both are imperforate. I have 
examined the animals, but could detect no specific distinction. 
T. tinEAaTus, Da Costa. 
T. lineatus, Brit. Moll. 1. p. 525, pl. 65. f.4, 5; as T. erassus. 
T. crassus, Auctorum. 
Animal inhabiting a strong, tumid, conically subdepressed, 
obliquely wrinkled, olivaceous, lineated shell of 5-7 volutions. 
Mantle even, but the pillar neck-lappet often forms a bran- 
chial fold, from which I have seen the water forcibly dis- 
charged. The head is a short, broad, compressed rostrum, 
with a transversely subarcuated, suboval disk, edged with 
short white fringe, not crenate, crosially cloven and furnished 
with the usual buccal apparatus; on the upper surface it is 
closely marked with dark brown irregular lines; the neck is 
pale brown. The tentacula are long, round, tapermg to 
nearly filiform extremities, rmged with palish purple lies, 
having the eyes, as in the tribe, on short distinct swollen 
pedicles. The foot at rest is oval, beneath pale drab, beauti- 
fully radiated with anastomosing white lines; on the march 
it is an elongated oval, rounded at both ends ; above, coloured 
like the muzzle, but of paler hue. The operculigerous lobe is 
very prominent, almost concurrent with the foot, of the 
same colour, plain-edged, carrying the usual orbicular multi- 
spiral operculum ; that is, when it preserves its normal form ; 
and on each side three vibracula, annulated, and of the 
