CANARIAN GROUP. 473 



leteness) of the spiral ribs, does not by any means tally with 

 his diagnosis ; for, instead of only ' four or five ' on the sub- 

 apical volutions (as he has recorded), I count, unmistakeably, 

 in one of the examples now before me, no less than ten, — thus 

 proving to a demonstration that the exact number of these 

 costse has (as in the numerous races of the G. cmxariense proper) 

 no specific signification whatsoever, and can scarcely be employed 

 to define accurately even the several insular varieties. How- 

 ever, considering that it also displays a sligld difference, not 

 merely in its somewhat more ovate outline but likewise in the 

 fact of its aperture being if anything a trifle less circular, I 

 am content to cite the C. Icevigatum as a separate species. 



With the exception of a few which are in the d'Orbignyan 

 collection at the British Museum, all the examples of tliis Cy- 

 clostoma which I have yet seen are in a bleached, though per- 

 haps not quite subfossilized, state,— which may indeed account 

 to a certain extent (the external cuticle having been much 

 destroyed) for the apparent obsoleteness of the spiral ridges. 

 Still I think there can be little doubt they are always absent 

 (or nearly so) except on the subapical whorls, — as, in point of 

 fact, appears to be the case in the few recent individuals at the 

 British Museum. 



The examples at present before me were taken by Mr. 

 Lowe, during our visit to Gfomera in February of 1858, up the 

 Barranco above San Sebastian. 



Cyclostoma canariense. 



Cyclostoma canariense, (.VOrh., in W. et B. Hist. 76. t. 2. 



f. 5 (1839) 

 Cyclostomus canariensis et adjunctus, 3Iouss., I.e. 144, 145 



(1872) 



Habitat (S. lanzarotensis, Woll.) Lanzarotam, ( s. adjunctus, 

 Mousp.) Canariam Grandem, (/3. raricosta, Woll., et y. in- 

 cequalis, Woll.) Teneriffam, (a. palmensis, Woll.) Palmam, et, 

 sec. cl. Fritsch, Hierro (saltern in statu seviifossili). 



After a careful consideration of a large assemblage of Ca- 

 narian Cyclostomas, collected in five different islands of the 

 archipelago, I have come to the , conclusion that tliey are pro- 

 bably all of them mere insular phases of a single plastic type ; 

 nevertheless, out of deference to previous monographers, I have 

 retained the Gomeran form (which is rather more peculiar 

 than the others) as specifically distinct, — deeming it sufficient 

 to record my conviction that it will be found eventually to re- 

 present but another race (somewhat more pronounced perhaps, 

 than the remainder, as to its features) of this eminently incon- 



