MADEIRAN GROUP. 170 



k. papilio, Lowe. 



Helix polymorph a, e. calcigena, Lowe, I. c. 56. t. 6. f. 15 



(1831) 

 „ „ ft, Pfeiff., Mai. Blatt. 81 (1852) 



„ papilio, Lowe, Ann. Nat. Hist. ix. 116 (1852) 

 „ „ Id., Proc. Zool. Soc.Lond. 190 ('1854) 

 „ polyrnorpha, var. i., Alb., I. c. 27. t. 6. f. 7-11 (1854) 

 „ testudinalis, a. minor, Paiva, I. c. 92 (1867) 



Habitat ins. parvam juxta Portum Sanctum ' Ilheo de Baixo ' 

 dictam ; in aridis calcareis vulgaris. Semifossilis quoque inve- 

 nitur. 



This is so near to the ' X. discina ' that I should hardly have 

 noticed it as a separate race had it not been published by Mr. 

 Lowe as a distinct species. However it is not quite similar to 

 that modification (as typically defined), it being somewhat inter- 

 mediate between it and the ' i. pulvinata.' Thus it is a little 

 less sharply keeled than the former, and perhaps not quite so 

 flattened, its surface is altogether paler or less brightly variegated, 

 and its granulations are nearly obsolete below, — where it has a 

 slightly shining or china-like appearance. And, as compared 

 with the latter (the ' i. pulvinata''), although not very different 

 from it in its somewhat pallid hue and but faintly dappled volu- 

 tions, it is a trifle more lenticular, or less conical, its keel is 

 rather more evident, and its upper portion is a little more finely 

 and densely granulated, whilst the lower one is comparatively 

 free from sculpture and even (as just mentioned) appreciably 

 shining. The peristome too is less continuous, the upper and 

 lower margins of it being wider apart, and almost unconnected 

 by a corneous plate. 



The ' k. papilio'' is the phasis which the H. polyrnorpha 

 assumes on the dry calcareous island adjoining Porto Santo known 

 as the Ilheo de Baixo ; and although occasional examples of 

 the ' X. discina,^ found elsewhere, may at first sight be scarcely 

 separable from it, yet as typically defined it must be regarded as 

 characteristic of that particular locality. 1 



X. discina, Lowe. 



Helix polyrnorpha, v ., Pfeiff., Mai. Blatt. 81 (1852) 

 „ discina, Lowe, Ann. Nat. Hist. ix. 117 (1852) 



1 Although so near (as just stated) to the 'k. discina ' as to be barely 

 separable from it, the Baron Paiva treats the present modification of the 

 //. polyrnorpha as a ' var. minor ' of the H. testudinalis, — one of the largest 

 and most distinct members of the Discula section, and one which would seem 

 to be better separated than almost any other from these immediate forms. 

 Indeed it appears to me (as it did to Dr. Albers) to be sufficient ly well defined 

 to merit specific isolation. 



N 2 



