308 TKOCHID^E. 



or T. Cutlerianus ; the general colour is pale bistre, with a 

 greater proportion of flake-white than in 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 Avith 

 the volutions much more tumid ; both are imperf orate. I have 

 examined the animals, but could detect no specific distinction. 



T. LiNEATUs,.Da Costa. 



T. lineatus, Brit. Moll. ii. p. 525, pi. 65. f. 4, 5 ; as T. crassus. 

 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, tapering to 

 nearly filiform extremities, ringed with palish purple lines, 

 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 



