184 TEST ACE A ATLANTIC A. 



Helix testudinalis, Pfeiff., Mon. Hel. iii. 161 (1853) 



Lowe, Proc. Zool. Soc. Land. 191 (1854) 



Alb., Mai. Mad. 25. t. 5. f. 4-^-6 (1854) 



Paiva, Mon. Moll. Mad. 91 (1867) 



Habitat Portum Sanctum ; in saxosis intermedus versus oram 

 borealem, prsecipue in regione Pedragal dicta, sub lapidibus. 

 Semifossilis in Campo de Baixo parcissime occurrit. 



The H. testudinalis (which measures about 8-J lines across 

 its broadest part) is the largest number of the Discula section 

 which has hitherto been brought to light in either the Madeiran 

 or Canarian Groups ; and it seems to be peculiar to a certain 

 limited district, known as the Pedragal, in the north of Porto 

 Santo, where it was first detected by myself and the late Rev. 

 W. J. Armitage, particularly on the promontory called the Ponta 

 de Guilherme, in 1 848, and where it was again met with by 

 Mr. Lowe and myself on the 21st of April 1855. In a subfossil 

 condition it is extremely scarce, though to be found occasionally 

 on the Campo de Baixo. 



Apart from its large size and open spiral umbilicus, the 

 present species (which is slightly shining and subpellucid, and 

 coloured somewhat after the manner of tortoiseshell ) may be 

 known by its flattened lozenge-shaped outline (the nucleus how- 

 ever of the spire being a little' papilliform or prominent), by its 

 keel being rather obtuse, and by its granules and transverse 

 lines being (particularly on the underside, where the former are 

 nearly evanescent) both fine and ininute, Its peristome, which 

 is recurved and internally white, has the margins wide apart and 

 merely connected by the thinnest possible intervening lamina ; 

 and its basal portion is of a clouded, or unequal, yellowish- 

 corneous hue, with a broad castaneous band encircling the 

 umbilical area, and the fragments of a second (obsolete) one 

 towards the keel ; whilst above, it is of a pale olivaceous brown 

 freckled with a few irregular cinereous transverse markings, and 

 ornamented with a more or less evident narrow castaneous medial 

 fascia which is usually traceable up the spire, an arrangement 

 of colouring which gives the volutions, at first sight, a very ob- 

 soletely subcarinated appearance about their central or dorsal 

 line. The ultimate whorl, which is deflected a good deal in 

 front, is more or Jess brightly ochreous outside the aperture. 



( Tectula, Lowe.) 



Helix Lyelliana. 



Helix Lyelliana, Lowe, Ann. Nat. Hist. ix. 117 (1852) 

 Pfei/., Mon, Hel. iii, 161 (1853; 



