212 SUPPLEMENT. 



body- whorl being larger in proportion to the others. Olnafirth 

 Yoe, Shetland. 



P. 141. — 0. DiAPHANA. E. G. Gascony (De Folin) ! 



P. 142. — 0. oBLiQUA. F. Uddevalla (Crosskey and Robert- 

 son) ! E. Quiberon, Brittany (Tasle) ! ; G. Naples (Stefanis)!; 

 Dabnatia (Brusina)! 



P. 143, for var. Warreni substitute 



0. Warre'ni*, Thompson. 



Body whitish, having a closely veined structure when ex- 

 amined microscopically : mantle folded at the upper corner of 

 the mouth of the shell : snout rather short, deeply bilobed : 

 tentacles leaf-like and proportionally large : eyes minute, close 

 together at the inner base of the tentacles : foot large, double- 

 edged and slightly auricled in front, deeply notched and bi- 

 lobed behind ; these lobes are equal in length and size, and 

 resemble the tail of a swallow. 



Shell more slender than 0. obliqua, covered vsdth very 

 numerous microscopic spiral striae, those at the base being 

 much stronger and more conspicuous, the apex obliquely trun- 

 cated, and the umbilicus deep. L. 0-1. B. 0-05. 



Habitat : Muddy sand, 50-80 f., N.E. and W. coasts of 

 Shetland. E. Naples, Taranto, and Sicily (Tiberi and Ste- 

 fanis) ! See also localities given in p. 143. Animal remark- 

 able for the forked extremity of the foot. It swims or floats, 

 like other small Gastropods, under the surface of the water ; 

 in which position the tentacles and lobes of the snout are not 

 unlike those processes in Jeffrey si a. One individual spun a 

 delicate glutinous filament from the foot, and kept itself sus- 

 pended for some time in the water, with the point of the shell 

 downwards. 0. acicula has the same habit. 



P. 144. — 0. DOLioLTFOPvMis. E. G. Naples (Stefanis) ! 



P. 145. — 0. DECtrssATA. F. Monte Mario (Rigacci) ! E. 

 G. Gascony (De Folin)! 



P. 148. — 0. CLATHRATA. F. Vienna basin (Mus. Yindob.)!; 

 Monte Mario (Rigacci) ! E. Algeria (Weinkauif) !; G. Naples 

 (Stefanis) !; Dalmatia (Brusina) ! 



* Named in compliment to the late Mr. T. W. Warren of Dublin, an 

 assiduous conchologist. 



