250 MARSHALL: ADDITIONS TO 'BRITISH CONCHOLOGY.' 



dredged off Southport in twelve fathoms with Philine nitida. 

 A live P. nitida was also dredged in the Isle of Man with 

 the Cyclostrema. The Southport specimen is twice the 

 size of the Oban one sent me, but is nevertheless a very 

 small object, about the size of our C. ?iitens. It differs 

 from the British Cyclostrema in its microscopic sculpture, 

 and especially in having the base keeled somewhat like 

 Adeorbis, in this respect resembling the C. excavata and 

 C. sulcatum of Watson, species taken during the' Challenger' 

 expedition. 



Trochus magus var. conica Marsh. Shell more simply 

 conical, having a raised spire, the whorls more compressed, 

 the suture much shallower, and the umbilicus smaller. 

 Harm Island, several specimens. 



T. tumidus var. minor Norman. I note this variety listed 

 in 'Museum Normanianum,' and take it to represent the 

 southern form, which is usually half the size of the northern 

 one. It has its counterpart in Pleurotonta costata, and its 

 northern representative var. coardata. Jeffreys' dimensions 

 of one-third-of-an-inch is for the northern form, while the 

 var. mittor is one-quarter-of-an-inch. 



T. cinerarius var. pallescens Duprey. See 'Annals' for 

 March, 1883. 



T. umbilicatus var. pallens Duprey. See 'Annals' for 

 October, 1876. 



Lacuna puteolus var. plicata Marsh. This must be ex- 

 punged from the List. Further specimens convince me 

 that its peculiar sculpture — fine transverse plated ribs — 

 is caused by the want of homogeneity in the structure of 

 the shell, and the consequent irregular wearing away of its 

 surface. Lacuna pallidula h?iS iht ?,zmQ iend^tncy. 



Lacuna pallidula var. naticiformis Marsh. Smaller and 

 thinner, rounded in outline ; body-whorl globular, and not 

 expanded in any direction ; spire prominent and pointed, 

 but short, projecting beyond the outline of the shell. 



J.C, vii., Oct. 1S93. 



