JEFFREYSIA. 61 



close together, and surrounded by pale rings ; they are visible 

 only through the shell: foot large, triangular, bilobed, and 

 slightly auricled in front, bluntly pointed behind. 



SHELL oval, extremely thin, semitransparent, highly glossy 

 and of an opaline lustre : sculpture as in the last species : colour 

 bronze or dark horncolour when the shell is living or contains 

 the remains of the animal, yellowish when it is empty : spire 

 short, with an abrupt and blunt point : whorls 3|, swollen, 

 rapidly enlarging ; the last occupies at least three-fourths of 

 the spire, and the first is mammiform : suture broad and deep : 

 mouth oval, capacious, and more than half the length of the 

 spire : outer lip sharp and thin, incurved above, slightly an- 

 gulated and expanding below : inner lip flexuous and thick- < 

 ened on the lower part of the pillar, behind which it forms a 

 narrow umbilical chink : operculum similar to that of J. dia- 

 phana; but the spike or apophysis is slightly curved, and oc- 

 casionally double, so as to make two separate leaves. L. O'l. 

 B. 0-075. 



HABITAT : Guernsey and Sark, in rock-pools among 

 Corallina officinalis (Barlee) ; Falmouth (Cocks and 

 Barlee) ; Cumbrae, Clyde district (Norman) ; Skye (A. 

 M'Nab) ; Whalsey Skerries, Shetland, on Laminaria 

 saccharina, a little beyond low-water mark (J. Gr. J.). 

 Although very local, it is abundant. I found a single 

 specimen at Lerici ; and Verany has recorded this species 

 from Nice. 



At the Whalsey Skerries it especially frequents a 

 sheltered part of the sound, close to a fish-curing station, 

 where the offal is thrown out. The other species of 

 Jeffrey sia and Trochus helicinus are its companions. Do 

 all these feed on decaying animal matter, or on Infu- 

 soria produced from it ? The spawn is deposited on 

 leaves of the Laminaria ; it is of a semioval shape, with 

 a large hole in the middle. When ripe it forms a thick 

 mass, and contains an immense number of yellowish 

 unispiral shells which are agglutinated together by a 

 gelatinous matrix. The adult shell resembles Hydrobia 



