456 Mr. W. Clark on the Conovulidse, 



which has its columellar edge raised and reflected outwardly 

 throughout its length, as in Chemnitzia diaphanay the nucleus 

 heing at the centre of the pillar edge, from whence the striae of 

 increment radiate conspicuously to the outer margin. The foot, 

 both above and below, the body generally, and the neck and head, 

 are of a rather opake white, sprinkled not very thickly but irre- 

 gularly with bright sulphur minute points. 



The animal is lively, moves with celerity, displays the organs, 

 and swims on its back. It is an inhabitant of the finer algse of 

 the pools of the lower levels of the littoral zone at Exmouth, in 

 considerable abundance. Mrs. Gulson, a lady naturalist at that 

 place, first made me acquainted with this species, by kindly con- 

 signing some specimens to my examination. It is a most poly- 

 morphous species, as out of nearly 100 specimens scarcely two 

 are alike, varying in tumidity, length, contour and colour ; indeed 

 every 100 yards of coast appears to have its peculiar variety. 



Chemnitzia plicata. 

 Turbo et Odostomia plicata, auctorum. 



The animal throughout is pale frosted yellow, inhabiting a 

 spiral shell of six or seven slightly raised volutions. Mantle sim- 

 ple. The head is a long, flat muzzle, with a circular, terminal, 

 entire, compressed disk, issuing between a tentacular veil and 

 the foot, and can be extended of concurrent length with the 

 latter organ. The tentacula are triangular, bevelled, broad, flat, 

 rather longer than in its congeners of the same size, and terminate 

 in rounded sublanceolate points ; the eyes are imbedded in the 

 skin at the internal bases, but not quite so close together as iu 

 some other species. Foot short, truncate in front, slightly notched 

 in the centre, labiated, rounded behind at rest ; somewhat elon- 

 gated, though not much pointed on the march ; carries the very 

 light horn- coloured operculum of suboval form, with oblique strise 

 of growth, on a simple upper lobe advanced to nearly the junc- 

 tion of the foot with the body. The foot has an inconspicuous 

 central longitudinal line on the sole. 



It inhabits in sufficient abundance the littoral zone at Ex- 

 mouth, but I believe it also inhabits the laminarian and coralline 

 districts. 



Chemnitzia rufa, auctorum. 

 Parthenia, Melania, et Odostomia rufa, nonnull. 



Animal inhabiting a shell of fourteen flat plicated volutions 

 with interstitial short transverse lines ; the general aspect as to 

 colour is pale azure hyaline, irregularly aspersed with snow-colour 

 opake flakes. The head or muzzle proceeds from the coalescing 



