MADEIRAN GROUP. 25 



tliin, almost colourless, and transparent substance, and by its 

 rather wide (or expanded) but nevertheless si-nn'ple (or basally 

 untruncate) arcuated columella. Although it has been found 

 sparingly (as just stated) on the two Southern Desertas, it is a 

 species wliich is more particularly characteristic of Porto 

 Santo, — where I have met with it in profusion, beneath stones, 

 on the exposed mountain ridge which connects the Pico de 

 Facho with the Pico do Castello. Mr. Lowe's original examples, 

 however, were from the Pico Branco. 



Lovea terebella. 



Achatina terebella, Lowe, Ann. Nat. Hist. ix. 120 (1852) 

 „ gracilis, a. terebella, et ^. subula, Lowe, Proc. Zool. 

 Soc. Lond. 200 (1854) 

 Glandina terebella, Alb., Mai. Mad. 6Q. 1. 14. f. 22, 23 (1854) 

 Achatina gracilis, a. subula, et 7. terebella, Pa^ya, Man. Moll. 

 Mad. 107, 108 (1867) 

 „ Lowei, Id., Ibid. 108 (1867) 



Habitat Portum Sanctum, — a. subula prsecipue in insulis 

 parvis adjacentibus ' Ilheo de Cima ' et ' Ilheo de Baixo ' dictis ; 

 sed /3 (normalis) in montibus excelsioribus Portus Sancti proprii, 

 prsesertim in Pico Branco occurrens. In arena calcarea, semi- 

 fossilis, parcissime invenitur. 



As already stated, the present Lovea, which seems to branch 

 off into two tolerably distinct forms, was regarded by Mr. Lowe 

 as conspecific with his Achatiiia gracilis; but I think it will 

 be more natural to treat it (as indeed Dr. Albers has done) as 

 separate from the latter. Indeed I am far from certain that 

 even the two phases into which it is supposed to develope would 

 not be isolated by some monographers ; though as they seem to 

 me almost to pass into each other, I will not attempt to dis- 

 associate them. The forms in question correspond with Mr. 

 Lowe's ' var. subula ' and ' var. terebella ' of his Achatina. 

 gracilis; and I should have preferred to retain the first of 

 those names, as perhaps expressing the species (as now limited) 

 the more accurately, had not that title been already preoccupied 

 by an Achatina by Dr. Pfeiffer {Wiegm. Ai^chiv. i. 352) in 

 1839, — thirteen years before it was employed by Mr. Lowe. 

 Hence, since ' terebella ' must of necessity be accepted as tlie 

 title, it follows that the particular shell to which Mr. Lowe 

 intended the latter to apply must be looked upon as the normal 

 aspect of the L. terebella as here understood. 



The two forms into which the L. terebella separates itself 

 (although nearly, as it seems to me, if not indeed quite, merg- 

 ing into each other) may be defined as (1) a smaller one, which 



