CHASTER : BRITISH MARINE MOLLUSCA. 



i7 



sides, younded ai the peripheyy, and markedly but bluntly angnlated 

 below, sculptured with numerous spiral roii's of verij minute pits or 

 punctures 7vhich, except at the periphery, are obscured by closely -set, 

 fle.xuous, oblique, raised striae in the direction of the lines of gro7uih ; 

 suture channelled ; mouth squarish ; outer lip thin, flexuous, sinuatcd 

 above : umbilicus very large, occupying all the under surface. — Height, 

 0-6 ;//;//. ; breadth, o-8 nun. 



FIGURE I. 



FIGURE lA. 



Adcorbis iiupcrspicnus, Monts. 



FIGURE 2. 



FIGURE 2A. 



^'•<v. 



Adcorbis siibcai-iitafus, Montg. 



Varictas ex forma, var. elegant ula, nov. In many specimens 

 the exaggerated lines of growth which in the type constitute a 

 true sculpture are almost absent, the shell being hyaline and 

 nearly smooth save for the characteristic punctation. In my 

 limited experience, such shells are of smaller size and may be 

 designated as above. 



Distribution. I have met with the type in dredgings from 

 Oban and Roundstone. Marshall records it from off Southport, ''"' 

 and Monterosato from Palermo and INIessina. 



The variety I have from Oban, Isle of Man, and Tangier 

 Bay (7 fathoms). As regards the retention of the name Adcorbis, 

 I follow Fischer and others, although the ^zrs/ species that S. Wood 

 gave in his newly-created genus, Adeorbis was the shell now 

 commonly known as Circulus striaius, Phil, which Monterosato 

 therefore styles Adeorbis stria tus. Ph. This is a matter upon 

 which I am entirely unable to decide, and one upon which I 

 should be glad to be informed authoritatively. 



Journ. of Conch., Oct,, 1894 ; Marshall. Additions to Brit. Conch. 



