192 DENTALIIDiE. 



an admixture of mud vnth. the sand in which this species 

 burrows : margui at the anterior or broader end more or 

 less jagged, owing to that part of the shell being newly 

 formed and consequently much thinner than other parts ; at 

 the posterior or narrower end it is usually truncated in adult 

 specimens, and furnished with a veiy short sloping and oblique 

 pipe or tubular appendage having a pear-shaped orifice; there 

 is also occasionally at the point on the convex side a notch or 

 groove, in a line with the front or smaller part of the tubular 

 appendage, and this notch is rarely extended into a short and 

 narrow slit or channel. L. I'o. B. 0-185. 



Var. anulata. Narrower and more regularly cylindrical, 

 ornamented with white ring-like marks of growth. 



Habitat : Gregarious in sand, from 3 f. to the 

 greatest depth explored on our coasts. Captain Beechey 

 dredged it alive in 145 f. off the MuU of Galloway. It 

 is much more common in the north than in the south. 

 The variety occurs in Shetland at a depth of from 85 

 to 90 f. Its ammlated appearance reminds one of the 

 testaceous sheath in certain species of Teredo. As an 

 upper tertiary fossil, D. entails is generally diffused both 

 in time and space, from the glacial " drift " to the red 

 Crag at home, and from the newer deposits in the 

 Christiania district, at a height of 100-150 feet above 

 the sea-level (Sars) to the miocene formation in the 

 Vienna basin (Homes). Its foreign distribution in a 

 recent state is also very extensive, although it is pro- 

 bable that D. Tarentinum has been mistaken for it in 

 compiling many local lists. Steenstrup collected it in 

 Iceland; Loven, Sars, and others in Scandinavia (4-200 

 f.); Mace at Cherbourg; Cailliaud in the Loire-Infe- 

 rieure; and H. Martin in the Gulf of Lyons; Olivi has 

 recorded it from the Adriatic, Maravigna and Scacchi 

 from Naples, Forbes from the ^gean, Mighels from 

 the State of Maine, and P. Carpenter from North- 

 west America. 



