458 Mr. W. Clark on the Conovulida3, 



with snow-white points of several magnitudes : the head is a mo- 

 derately long muzzle, flat, plain, rounded in front ; it issues from 

 the tentacular membrane, and is placed between it and the foot, 

 with which it is of concurrent length ; on the march sometimes 

 one and sometimes the other is in advance, but the tentacula 

 always reach beyond the head, which only very rarely, by an ex- 

 traordinary exertion, is extended to the tentacula : I mention this 

 because I have seen the animal figured with the muzzle as long 

 as the tentacula, which is an unnatural posture, and it is never 

 carried so on the march ; the mouth is beneath. The tentacula 

 occupy the extent of the membrane from which they originate, 

 coalescing at their bases, and diverging greatly to their points ; 

 they are short, flat, broad, bevelled, triangular, blunt, setose, with 

 a snow-white line from base to point, and a round intense flake- 

 white dot at their tips, which give them the aspect of being cla- 

 vate ; the eyes are large, black, placed on the skin at the internal 

 bases of the tentacular bifurcation. The foot is slightly auricled, 

 and sinuated on each side so as to make a gradual central inden- 

 tation ; it is rather broad, perfectly round posteally at half exten- 

 sion, but in full march it tapers to a moderately pointed lan- 

 ceolate termination, carrying on a plain upper lobe a suboval, 

 light corneous finely striated simple operculum. The animal is 

 active, and shows its points sansfaqon. It inhabits at Exmouth 

 the coralline, laminarian, and the lowest littoral levels. It scarcely 

 differs from C rissoides, except in being white instead of speckled 

 with yellow, and in the foot being sinuated in front instead of 

 truncate. There is, usually a fold on the pillar. 



Chemnitzia interstincta. 



Turbo et Odostomia interstincta^ Mont, et auct. 



^^. Animal inhabiting a flat subcylindrical shell of six to seven 

 volutions ; it is white throughout. Mantle rather fleshy around 

 the margin of the aperture ; head narrow, cloven, with exceed- 

 ingly short, strong, rather flat, setaceous, very obtusely pointed 

 tentacula ; the eyes are very distinct at their internal bases, not 

 in the least raised; foot very small, short, and does not extend 

 beyond the basal volution, truncate in front, moderately pointed 

 behind, carrying on its upper surface a minute light corneous 

 simply striated operculum. It inhabits the coralline zone, lurk- 

 ing in the crevices of the Annelida, in old bivalve shells. The 

 species now described is the variety with the subrotund volutions, 

 and of larger growth than its slender subcylindrical congener 

 with the flat angular sutures, which possibly may be distinct ; 

 but it is probable I may meet with the animal. This species is 

 frequently without the fold; we have many such in our cabinet. 



