160 TEST ACE A ATLANTIC A. 



(sc. quasi maxima), et forsan ejus statvis antiquus, hodie 

 extinctus. 



Habitat Portum Sanctum, semifossilis ; recens baud obser- 

 vata. 



The above diagnosis has been compiled from a few subfossil 

 specimens which we obtained when in Porto Santo ; and with 

 the exception of their size being comparatively gigantic, they 

 appear to possess nearly all the characteristics of the H. echinu- 

 lata ; but since their stature is so monstrous as compared with 

 that of the latter (which is more constant than in almost any 

 Helix with I am acquainted), I cannot but suspect that they 

 must represent some large extinct species which stands in pre- 

 cisely the same relation to the echinulata as the subfossil H. 

 vermetiformis does to the bicarinata, or as the subfossil H. 

 Loivei and Bowdichiana do to the recent H. 'portosanctana 

 and pimctulata. At any rate, each of these forms occupies a 

 similar position with reference to its own particular analogue, 

 and as species they must either stand or fall together. 



Helix echinulata. 



Helix echinulata, Loiue, Camhr. Phil. S. Trans, iv. 57. t. 6. 

 f. 19 (1831) 

 „ „ Pfeiff., Mon. Hel. i. 189 (1848) 



„ „ Loiue, Proc. Zool. Soc. Loud. 186 (1854) 



„ „ Alb., Mai. Mad. 36. t. 9. f. 5-7 (1854) 



„ bicarinata var., Paiva, Mon. Moll. Mad. 45 (1867) 



Habitat Portum Sanctum ; sub lapidibus in montibus, 

 vulgaris. 



A roughened, or asperated, somewhat Trochiform little 

 Helix, which, together with the (prinid facie almost similar) 

 H. bicarinata, is very abundant, beneath stones, on the moun- 

 tains of Porto Santo, and one which may readily be known, 

 apart from its small size and very coarsely tubercled (or well- 

 nigh sub-spinulose) surface, by its reddish-brown hue (which 

 however usually appears darker than it really is, on account of 

 the entire shell being more or less powdered with a rusty deposit 

 from the earth with whicli it is found in contact), by its sub- 

 conical upper- and flattened under-portions, and by its puncti- 

 form umbilicus and its circular aperture, — the peristome of 

 which is continuous and appreciably elevated or raised. Its 

 volutions (which are convex, and seldom exactly banded) will be 

 seen, when cleaned, to have a few conspicuous darker clouds, or 

 suffused ill-defined dashes (rarely amounting to anything like a 

 band, and some of them lonfjitudinalli) disposed) at irregular 

 intervals ; and tlie basal one is sharply keeled, with its compara- 



