252 TEST ACE A ATLANTIC A. 



is likewise relatively narrower and more acute, and with the lip 

 of the aperture less externally-rounded, — the ^ var. subula^ of 

 Lowe; and (2) another, which is appreciably larger and more 

 ventricose and convex, and with the outer lip more rounded 

 posteriorly (causing the aperture to be a trifle wider and alto- 

 gether more developed), — which corresponds with the ' var. 

 terebella^ of Lowe's Achatina gracilis. The first of these 

 phases I have taken abundantly on the islands adjoining Porto 

 Santo, known as the Ilheo de Cima and the Ilheo de Baixo, as 

 well as on the Pico de Baixo (of the mainland) exactly opposite 

 to the former ; whilst the second occurs at a higher altitude, 

 and has been found principally, so far as I can now recollect, on 

 the Pico Branco. 



In a subfossil condition the L. terebella appears to be scarce, 

 and the few examples of it which I possess are somewhat inter- 

 mediate between the states above alluded to ; though on the 

 whole I think that they agree better perhaps with the a. subula 

 than with the larger (or typical) form. 



Were I to judge solely from six examples which are now 

 before me, and which were communicated by the Baron Paiva, 

 the ^Achatina LoweV of the latter (recorded by him from the 

 Pico Branco in Porto Santo) is absolutely identical with the 

 common L. oryza, — there being no difference in them what- 

 soever, so far as I can detect, on which to found even a 

 ' variety.' Nevertheless I am so satisfied, from the Baron's 

 diagnosis, that the species to which he really alluded is the 

 larger (or normal) phasis of the L. terebella, that I have not the 

 slightest hesitation in referring his Achatina Lowei to that 

 particular form. Indeed his following diagnostic observation 

 expresses so exactly the precise points in which the L. terebella 

 differs from the oryza that I quote it verbatim: — ^ A. oryza, 

 Lowe, quodammodo analoga ; testa vero tenuiore, apertura 

 arapliore, pariete aperturali tuberculo destituta distinguitur.' ' 



Lovea oryza. 



Helix triticea, jB. edentula, Lowe, Cambr. Phil. S. Trans. 



iv. 61. t. 6. f. 26 (1831) 



' There is a ' var. 5. ventricosa ' of the L. r/racilis which is recorded by the 

 Baron Paiva as having been taken by Mr. Watson on the Ilheo de Fora, at tlie 

 extremity (in Madeira proper) of the Ponta de Sao Lourencjo, and which, 

 from its being placed by him in juxta-position witli the terebella, ought here 

 to be noticed. Having no type for comparison, I am not able to satisfy my- 

 self concerning its affinities, and I deem' it snfhcient therefore to call atten- 

 tion to the fact, that either the L. terchdla or some closely allied form ap- 

 j)ears to exist on the particular point of Madeira proper which is nearest to 

 the island of Porto Santo. 



