374 TEST ACE A ATLANTIC A. 



spite of the great aberrational range of the pisana, I think that 

 the H. impugnata recedes from it in so many particulars, and 

 so conspicuously, that we may fairly be permitted to cite it as 

 distinct ; though, at the same time, I cannot but feel that 

 another mode of treatment is at any rate possible. The U. im- 

 pugnata is a solid and (in its normal condition) a very acutely 

 keeled species, the keel being subcrenulate and filiform (or 

 shaped out by a slight concavity on either side) and traceable 

 up the (depressed) spire ; its basal region is comparatively con- 

 vex ; its surface is almost opake, and roughened, being strongly 

 sculptured with the usual decussating striae (the spiral lines of 

 which are exceedingly apparent) ; and its perforation is nearly 

 closed. In the 6 var. subgeminata ' the keel is much less sharply 

 expressed, and the spire is less flattened. 1 



From the ' var. Grasseti ' of the pisana (to which it is more 

 particularly allied) the H. impugnata differs in having the keel 

 acuter, as well as more prominent and filiform (being scooped 

 out on either side) ; in its spire being a little less flattened, its 

 sculpture coarser, its surface more opake, its basal volution (es- 

 pecially towards the aperture) less ventricose, and its columellary 

 margin somewhat less vertical. Its colour too is different, 

 being less lively and defined, the markings being more obscure 

 and fragmentary, and toned-down with a suffused yellowish- 

 brown. 



( XerojjJiila, Held.) 



Helix lineata. 



Helix lineata, Oliv., Zool. Adriat. 177 (1799) 



maritima, Drop., Hist. Nat. 85. t. 5. f. 9, 10 (1805) 

 W. et B., Ann. des Sc. Nat. 28. syn. 316 



(1833) 



simulata, W. et B. [nee Per."], I. c. syn. 315. t. 24. f. 1 

 (1833) 2 



1 It is remarkable that two precisely analogous states of the shell occur 

 in the true If. planata, Chemh., from Mogador ; and they were well denned 

 by Mr. Lowe (vide 'Zool. Journ.,' 1860, pp. 196, 197) as the 'a. acutangula' 

 and the ' &. obtusangula.' 



2 Mousson (I. c. 34) raises the question as to whether the H. simulata, 

 W. et B. [which however is not the simulata of Ferussac, a species purely 

 oriental], may not be identical with the scarcely differing state, or variety (?), 

 of the lineata to which Shuttleworth appears to have applied the MS. name, 

 ' canariensis ; ' and to this I would reply that the H. simulata, W. et B., is 

 simply and purely the H. lineata, Oliv., in its normal Caiaarian aspect. Mr. 

 Webb's examples were, in point of fact, collected by himself in the El Monte 

 district of Grand Canary, and some of them he transmitted to Mr. Lowe in 

 August, 1829 ; and in a note, now before me, written by Mr. Lowe in 1833, he 

 (Mr. Lowe) identified them, without any doubt whatsoever, with the //. ma- 

 ritima, Drap., which indeed is the universal species of the El Monte region, 

 differing only from the more northern type in the few and very insignificant 

 points to which I have called attention. 



