PLEUROTOMARIA. 403 



1873. Pletjrotomaria Agatha, d'Orhigny. Tawney, Dundry Gasteropoda, p. 



40 (32). 

 Syn. — mutabilis, var. cojlata, Deslongchamjis. Vol. cit., 



p. 109, pi. x, fig. 17. 



Bibliography, 8fc.—lt is through the figure rather than the description that 

 English specimens are connected with the var. ccelata of Deslongchamps. On the 

 other hand, as pointed out by Tawney, d'Orbigny's figure more nearly resembles 

 the var. corrugata than the var. coelata of Deslongchamps. The principal 

 characters by which I recognise PI. Agatha are (1) the nodular character of the 

 carinas, and (2) the coarse ornamentation of the intercarinal spaces. 

 Description : 



Height (full size) . . . .50 mm. 



Basal diameter . . . .50 mm. 



Spiral angle .... 60°. 



Shell conical, thick, not umbilicated. The spire is slightly concave. The 

 whorls are flat, but owing to the prominence of the carinas in some cases appear 

 to be concave. The suture is extremely close. In the more typical forms the 

 carinas are coarsely nodular, and the intercarinal grooviugs (spiral) are deep and 

 coarsely decussated. 



The sinus-band is narrow, flat, and inconspicuous, and situate very close to 

 the basal rim or carina. The body-whorl is more or less angular at the periphery, 

 the base varying from rather flat to subconvex with spiral strias. The aperture 

 is subdepressed, with an oblique inner lip and but slight trace of the columellar 

 notch. 



Var. Sanders ii, Tawney. 



1S73. Pletjrotomaria Sandersii, Taivncy. Dundry Gasteropoda, p. 39 (31), 



pi. iii, fig. 1. 



The indications, as noted by Tawney, are very much those of Deslongchamps' 

 var. coelata. But the whorls and also the base are more convex. The sinus-band 

 also is very sunken and fiat. 



The unique specimen on which this variety is founded comes from Dundry. It 

 is in a highly crystalline condition, a circumstance which may partly account for the 

 peculiarities of the sinus-band. 



