150 HELIX. 



H. GRATELOUPI Graells, 1846. PJ. 48, figs. 94, 95. 



Imperforate, depressed globular, rather thin, shining, whitish- 

 corneous, or suffused with light brown, with five distinct narrow 

 chestnut-brown bands, frequently interrupted, or broken into nearly 

 separate mac illations, very lightly obliquely striate ; whorls 4, con- 

 vex, very rapidly increasing, the last rotund, gently descending 

 anteriorly ; aperture rounded-lunar, very oblique, its margins con- 

 verging, joined by a transparent parietal callus ; peristome thin, 

 acute, slightly expanded, regularly arcuate, columellar margin con- 

 cave, adnate to the rather inflated base, and slightly tinged with 

 brown. Diam. 21, alt. 16 mill. 



Majorca, Balearic Is. 



H. tessellata Fer. and H. graellsiana Pfr. are synonyms. 



Section V, HEMICYCLA Swainson, 1840. 



This group of large Helices is intermediate in conchological 

 characters between Macularia and Leptaxis, and rather closely allied 

 to both. In distribution it is restricted to the Canary Archipelago, 

 no species being found outside the limits of that group ; and it is 

 the most prominent form of Helix in the mollusk fauna of those 

 islands, occupying them to the exclusion of Iberus, Leptaxis and 

 (almost) of Macularia. Several species very similar to recent forms 

 are found fossil in central European mioceue deposits, associated 

 with Macularia, Clausilia, Melanopsis, etc. 



There is a similarity between some species of Hemicycla (such as 

 H. malleata) and certain West Indian forms of Deutellaria, (H. 

 obesa, H. dentiens) ; this resemblance is more likely to be due to con- 

 vergence of type, caused by similar environments than to any close 

 relation or connection between these specialized forms ; and the same 

 may be safely said of the superficial likeness which the African Macu- 

 laria jobaeana bears to the West Indian Dentellaria formosa, etc. 



The species of Hemicycla are very numerous, and frequently sep- 

 arated by characters so slight as to render it very likely that the 

 number of species bonce would be considerably reduced by a critical 

 study of the intermediate forms and the variations produced by 

 peculiarities of station, hypsometical distribution, etc. Such a study 

 however, we are not likely to have as long as the great majority of 

 land-shell specialists pursue the intensely analytical methods now in 

 voo-ue. 



