CAPE-VERDE GROUP. 503 



MaL Bldtt. under the name of serta. Still, since the H. serta 

 has already been published, and it is just possible to distinguish 

 it, in a general way, both as regards colour and sculpture, I will 

 not attempt to do more than record my belief that it will be 

 found eventually to be but a local aspect of the advena. 



After these observations I will merely remark, that, judging 

 from a long array of individuals which are now before me, the 

 H. serta would appear to differ from the advena, merely, in 

 being just perceptibly less coarsely striate (at any rate than the 

 S. Vicente type), and in its colour being both more varied and 

 with less of the leaden, or blueish, tinge which characterises the 

 latter in its normal condition. Perhaps too its umbilicus is, if 

 anything, a little less decidedly "closed over, though this is a 

 feature which is eminently inconstant. Its bands, however, are 

 (on the average) very much narrower, as well as more broken-up 

 and irregular, which causes the entire surface to seem paler 

 and much more variegated, or dappled. 



The H. serta (if indeed it be more than a phasis of the ad- 

 vena) was taken by Mr. Lowe and Dr. H. Dohrn in S. Nicolao, 

 namely in the Euphorbia region on the declivities of Monte Grordo. 



Helix Visgeriana. 



Helix Visgeriana, Dohrn, MaL Bldtt. xvi. 6 (1869) 



Morel., Journ. de Conch, xiii. 242 (1873) 



Pfei/. 9 Mon. Hel vii. 330 (1876) 



Habitat S. lago ; in montibus a cl. Dohrn reperta. 



The present species and the H. fogoensis, although on the 

 advena type, possess a peculiarity of sculpture which will serve 

 to separate them from the preceding ones, in the presence of 

 extremely minute spiral thread-like lines, which are more or 

 less visible between the oblique transverse costse. In the H. 

 Visgeriana, however, which is (on the average) rather smaller 

 and less globose (indeed it is the smallest of these immediately 

 allied species), the minute spiral lines are much more, and 

 the oblique transverse ridges are very much more, strongly 

 developed ; in addition to which, the ribs, being for the most 

 part of a pallid hue, and therefore breaking-up or intersecting 

 the darker bands, impart a remarkably variegated appearance 

 to the entire surface. 



The H. Visgeriana, which has been communicated by Dr. 

 H. Dohrn, was detected by him at a high elevation in the 

 island of S. lago. 



Helix myristica, 



Helix myristica, ShuttL, Bern. Mitth. 292 (1852) 

 Pfeiff., Mon. Hel. iii. 645 (1853) 



