Mr. R. T. Lowe on a new Madeiran Helix. 45 



In the paler violet-grey or chalky-whitish-shelled examples, 

 the animal is much paler than in the brownish flesh-coloured 

 or purplish-shelled individuals. 



Shell rather thin, light, and fragile; opake, but pellucid when 

 held up to the light ; of a uniform peculiar dull-brownish 

 flesh-colour or livid purplish, sometimes, even in living exam- 

 ples, of a pale violet-grey or lead-colour or chalky-white, en- 

 tirely without lustre or polish. Shape planorbiform, orbicular, 

 depressed, with the spire flattened and but slightly convex, 

 sharply keeled whilst young, but either without any keel or ob- 

 scurely double-keeled when adult, the keel minutely but not 

 regularly toothed in the young shell. The sculpture is very 

 elegant and complex : above, the volutions are regularly and 

 distinctly, but not strongly, plaited at their upper edge with 

 short, equidistant, oblique ribs radiating from the suture about 

 half-way across their breadth ; beneath, they are very regularly 

 and strongly ribbed and grooved spirally, the somewhat broad 

 or flattened ribs being also beautifully cancellated by regular, 

 sharp, equidistant, annular or transverse finer riblets. Whilst 

 there is only one larger or more prominent spiral rib above the 

 evanescent keel on the last volution, there are usually about 

 eight or ten below it ; and sometimes the uppermost of these is 

 stronger and a little remote, and separated by a broader or 

 deeper groove from the rest below, forming a sort of secondary 

 lower keel. Again, on the upper side the volutions, and espe- 

 cially the last, are often marked with flexuose or zigzag, very 

 oblique waved striae, as in H. Delphinula -, and on both sides 

 they are found, under the lens, to be covered with excessively 

 fine and thickly crowded, close-set, transverse strise, passing 

 along the annular and across the spiral ribs and their inter- 

 stices. Thus, in well- developed individuals, there are four di- 

 stinct systems of sculpture, viz. the spiral and annular ribs, 

 and the flexuose and microscopic strise. 



In shape and general aspect, H. delphinuloides bears a marked 

 resemblance, as already mentioned, to some of the flattened 

 discoidal Cyclostomata, and in colour it is often very like C. ele- 

 gans f Mull. The large, open, spiral, beautifully grooved and 

 cancellated umbilicus recalls to mind that of the marine genera 

 Solarium and Delphinula, Lam. ; and it is as much with reference 

 to this analogy as to its affinity with Helix Delphinula, Lowe, 

 that I have named the species. 



H. delphinuloides is at once distinguished from H. Delphinula 

 by wanting the sharp, thin, broad, projecting, rim-like keel ; by 

 its flattened discoidal shape, and wider, shallower umbilicus : 

 and from its much nearer ally, the Desertan fossil, H. coronula, 

 Lowe, it differs in being more than twice as large ; in the flat- 



