124 TEST ACE A ATLANTICA. 



mixed up with which it is so frequently found, at, and about, 

 the bases of the perpendicular rocks. 



Helix Latinea. 



Helix depauperate, var. /3., Alb., Mai. Mad. 33 (1854) 

 „ Latinea, Paiv a, Journ. de Conch, xiv. 341. pi. 11. 



f. 7 (1866) 

 „ „ Id., Mori. Moll. Mad. 58 (1867) 



Habitat Portum Sanctum, semifossilis ; in arena calcarea 

 vulgaris. 



At first sight this species, which seems to occur only in a 

 subfossil state in Porto Santo (where it is extremely abundant 

 in many of the calcareous deposits), might be looked upon as a 

 variety either of the H. depauperata or of the obtecta, — to both 

 of which it is very closely allied ; nevertheless, after a careful 

 consideration of its distinctive characters, I do not quite see 

 how it can be referred to either of them, — though, on the whole, 

 I think that it has more in common with the latter than with 

 the former. 1 



Although agreeing with the H. obtecta in its larger size, 

 ruder sculpture, more circular aperture, and elevated, continu- 

 ous peristome, the H. Latinea is nevertheless totally unkeeled, 

 and possesses a still wider and more spirally open umbilicus, and 

 that too in combination with the regular spire (though it is 

 not quite so much elevated) and somewhat more numerous 

 whorls of the depauperata, — thus wanting entirely the anoma- 

 lously depressed, subconcave apex, but nevertheless deep suture 

 and prominent volutions, which form so striking a feature in 

 the spire of the H. obtecta. 



On the other hand, when compared with the depauperata 

 (of which Dr. Albers has cited it as a 'var. /3.'), the H. Latinea 

 is considerably larger and more depressed, its umbilicus is very 

 much wider, more spiral, and more open, and its aperture is 

 more decidedly rounded, — the peristome being both more raised 

 and more continuous. Its general surface, too, is a little more 

 coarsely sculptured, — though perhaps not quite so uneven as 

 that of the H. obtecta. 



1 This was also the opinion of Mr. Lowe, to whom in March of 1856 I 

 forwarded an example which had been communicated to me by Mr. Leacock. 

 That single specimen (which was all that he had to judge from) Mr. Lowe 

 was inclined to regard as ' a curious monstrosity of the H. obtecta, of which it 

 possesses the large umbilicus, the more constricted aperture, and the coarser 

 sculpture, combined with the regular cjjire of the //. depauperata.' But could 

 he have seen the shell in sufficient numbers, I feel sure that he would have 

 come to the conclusion that it is no mere 'monstrosity,' but as true and con- 

 stant in its characters as any of these irnniediately-allied species. 



