348 NASSID.E. 



horncolour, serrated on the outer edge, and often also on the 

 inner edge near the base ; the serrature arises from the laminae 

 of which the operculum is composed being spinons or angu- 

 lated at their external margins ; lines of growth numerous and 

 obliquely elliptical. L. 1-25. B. 0-7. 



^ 



HABITAT : Sand at low-water mark, and in the lami- 

 narian zone, throughout the British Isles; common. 

 It occurs in many of our quaternary deposits, including 

 those at Selsea, Moel Tryfaen, and Belfast ; Norway, 

 0-440 feet (Sars); Uddevalla (J. G. J.); Baltic pro- 

 vinces of Prussia (Lehmann, fide Rosmer) ; French and 

 Italian tertiaries (Basterot, Brocchi, and others); marine 

 beds of the Vienna basin (Homes) . An inhabitant of 

 the North Atlantic (from Bejan near Drontheim to 

 Gibraltar) , the Mediterranean, Adriatic, and Black Sea, 

 at depths of 0-70 f. 



The "small latticed Whelk" of Petiver. At the 

 recess of each tide this mollusk buries itself in the sand 

 in a slanting position, its lurking-place being betrayed 

 by a little hillock. It also gets into lobster-pots, for 

 the sake of the bait. Bouchard-Chantereaux attributes 

 to this, as well as to other whelks, the habit of piercing 

 and devouring bivalves. According to M. Lespes N. 

 retiadata is preyed upon by a parasitic Trematode (Cer- 

 carla sagittata} which infests its liver. Its spawn-cases 

 are deposited on the leaves of Zostera and on various 

 other things which are left dry only at spring tides ; the 

 capsules are arranged in rows, and so closely that they 

 overlie each other "like the brass scales of the cheek-band 

 of a hussar " (Johnston) . They are compressed pouches, 

 each of the size of a large spangle, supported on a very 

 short stalk, with a small opening at the top to allow the fry 

 to escape, Mr. Peach described and figured the capsules 

 in the Reports of two Cornish Societies for 1843 and 



