ODOSTOMIA. 123 



not much expanded nor at all angulated below ; it usually 

 equals in length two-fifths (sometimes nearly one-half) of the 

 spire : outer lip curved and rather prominent : inner Up very 

 slight on the upper part, forming a mere film on the pillar, 

 thickened and somewhat reflected on the lower part: umbilicus 

 usually none, although in specimens which have a short spire 

 there is a more or less developed chink or indentation : tooth 

 small and partly concealed: operculum like that of 0. albella. 

 L. 0-125. B. 0-0625. 



Yar. 1. alba. Thinner; spire produced; suture deeper and 

 more oblique ; umbilical chink very distinct. 0. alba, Jeflr. 

 in Ann. & Mag. jS". H. 2nd ser. ii. p. 337, and 3rd ser. iii. pi. iii. 

 f. 20, a, b. 



Yar. 2. nitida. Whorls more ventricose, and umbilicus 

 distinct. 0. nitida, Alder, in Ann. & Mag. IS". H. xiii. p. o26, 

 pi. viii. f. 5 ; F. & H. iii. p. 280, pi. xciv. f. 6. 



Yar. 3. glabrata. Nearly oblong ; nucleus of spire exposed 

 and mammillary ; suture deep. O. glabrata, F. & H. iii. p. 233, 

 pi. xcviii. f. 3 (not Helix glabrata of v. Miihlfeld, nor Rissoa 

 glabrata — afterwards punctulum — of Philippi) . 



Yar. 4. dubia. Oval, and of a more solid consistency ; body- 

 whorl longer than usual ; umbilical chink distinct ; tooth 

 stronger and rather more conspicuous. O. dubia, Jefir. in Ann. 

 & Mag. N. H. 3rd ser. ii. p. 338. 



Yar. 5. exilis. Smaller and more slender; spire elongated, 

 and suture slight. 



Habitat : The lower part of the littoral zone and 

 throughout the laminarian zone, on all our coasts. 

 Yar. 1. Oxwich Bay near Swansea, Guernsey, Skye, 

 and Shetland (J. G. J.) ; Sark (Baiiee) ; South Devon 

 (Webster); co. Antrim (Waller). Var. 2. Shetland 

 (Barlee) ; South Devon (Webster) . Var. 3. Tynemouth 

 (Alder) . Var. 4. Lower part of the laminarian zone in 

 many places. Var. 5. South Devon (Webster). The 

 foreign localities are Bohuslan (Loven, in mus. Stockh.) 

 and 15-30 f. (Malm, as O. albella) ; Danish coasts (mus. 

 Copenh.) ; Etretat (J. G. J.) ; Morbihan (Tasle) ; Loire- 



g2 



