146 SYSTEMATIC ARRANGEMENT 



each side about seventy, the first by far the longest, gradually dimi- 

 nishing, hooked, pointed, denticulated behind at the bend, in the 

 first externally hollowed, in the last obsolete; scape of the first 

 wide, winged within, in the remainder simple, the middle produced 

 within. 



The neck-lappets of Hutropia pulla subcircular membranes ; the 

 right is the largest, margined with twelve or fifteen distinct cirrhi of 

 almost equal length, and fimbriating the sides ; the left has only eight 

 or ten cirrhi. The operculigerous lobe is almost coextensive with 

 the foot ; it is furnished with three densely ciliated, flatfish, pointed 

 vibracula on each side ; the middle ones are very short and incon- 

 spicuous ; each bifid. The branchial plume is single, arcuated, with 

 numerous close-set transverse vessels at the anterior end, which are 

 long at their commencement and taper gradually to near the peri- 

 cardium, as in LittoriruB. The lateral vibracula two or four, long, 

 setose. Neck-lappet scalloped, with six or nine dentations or cirrhi, 

 more developed on the pillar side. It walks like Cyclostoma elegans 

 and some LittoriruB, by one-half of the longitudinal area bounded by 

 a central incised line being extended and fixed ; the other half is 

 then brought up, and in like manner fixed, while the first half makes 

 a progression, and so on. Thus half the foot is alternately in motion, 

 giving the animal a lateral oscillatory progress. — Clark, Moll. 321. 



Fam. IV. LIOTIAM. 



Operculum horny, with an external calcareous coat formed of 

 numerous separate, pearl-like, shelly particles placed in spiral lines. 

 Shell discoidal, white, spirally grooved or concentrically ridged. 

 Aperture orbicular, more or less pearly within. 



a. Body of animal and whorls cylindrical, rounded. 



1. LlOTIA. 



Shell variced ; axis perforated or umbilicated ; aperture circular ; 

 throat pearly ; lips thick. 



1 . L. granulosa. Delphinula g., Bunker. 



2. L. Kraussii. Solarium cancellatum, Krauss. 



3. L. cancellata. Delph. c, Gray = D. Cobiensis, Reeve. 



The head of Liotia pulcherrima is proboscidiform ; the tentacles 

 subulate ; the eyes on conspicuous peduncles at their outer bases ; 

 there are no intertentacular lobes, but a conical lobe on each side of 

 the head external to the eye-peduncles ; lateral membrane of the 

 foot undulated, and furnished behind with three cirrhi. The opercu- 

 lum is arctispiral ; the volutions being very narrow, numerous, and 

 covered with a calcareous deposit which is articulated at regular in- 

 tervals, giving the upper surface of the operculum a tessellated ap- 



