NER1TACEA. MOLLUSCA. NATICA. 233 



E'schara lutosa, PALLAS ; EL Zooph., 37, No. 5. 



E'schara millepora arenosa A'nglica, RAY; Syn., 31. 



Alcyuniiim iirrnosinn, GMELIN ; Syst. .Vat., iv. (4. SHAW ; .\at. Miscell., t.272. 



Discopora cribrum, LAM.; An. sans t'crt., ii. 250. 



NATICA TRISERIATA. 



Shell ovate-globose, whorls five, usually checkered with three 

 series of dark spots on the lower whorl, and one on the upper whorls ; 

 umbilicus small, nearly free. 



FIGURE 165. 

 State Coll., No. 60. Soc. Cab., No. 1519. 



Natica triseriata, SAY ; Journ. Acad. Nat. Sc., v. 211. 



Shell ovate, approaching to globular, of a yellowish-white or 

 ash-color ; whorls five, convex, lines of growth distinct, and 

 usually covered with a thin yellowish epidermis ; lower whorl has 

 three revolving series of twelve to fourteen bluish or dark 

 chestnut-colored, oblique spots, usually of a square or oblong 

 form, and sometimes crescent-shaped ; the upper one just below 

 the suture ; the middle one is divided by the junction of the lip, 

 and the third is half way between it and the umbilicus ; the upper 

 one is continued on all the whorls, but the next one disappears 

 soon ; the spaces between the spots often appear like whitish 

 bands, and the sutural region is of the same color ; spire con- 

 siderably elevated, sutural line delicate ; aperture ovate, lip sharp 

 and white within ; a thick white callus covers the inner margin, 

 very slightly modifying the umbilicus, where it has a fissure at the 

 posterior margin of the umbilicus ; a dense mass of callus, within 

 the aperture, at its upper angle, strengthens the lip ; throat 

 colored with dark-chestnut, or transmitting the exterior mark- 

 ings ; umbilicus rather small and simple, not much wrinkled 

 within ; operculum horny. Length T 7 T inch, breadth J inch. 



Found along the whole coast to the north of Cape Cod, on 

 flats which are left by the tide at low water ; but it is as yet 

 doubtful whether it passes to the south of this limit. 



This has been thought by some to be the young of the preceding 

 species. In general aspect there is a resemblance ; but the proper- 

 30 



