556 TESTACEA ATLANTIC A. 



This and the >S'. 'picta are the largest of the island Succineas 

 (measuring from about 7 to 8 lines in their greatest length, 

 with an altitude of about 3), the 8. Sanctce-Helence being emi- 

 nently characteristic of the most elevated portions of the central 

 heights, — where it swarms on the foliage of the various species 

 of Cabbage-tree about Diana's Peak, Actseon, and Stitch's Kidge. 

 In the more western parts, however, of the great medial crater- 

 wall, around High Peak, its place seems to be taken by the very 

 closely allied form which I have cited as the S. picta, Pfeiff. 



Apart from its large stature (when fully matured), the S. 

 Sanctce-Helenoe may be known by its perfectly enormous basal 

 volution and aperture, and its extremely minute, papilliform 

 spire. Its transverse lines of growth are coarse but very irre- 

 gular ; its substance (as in most of the Succineas) is thin, 

 flexible, and pellucid ; its surface is generally very uneven, and 

 slightly shining ; and its colour (as is equally the case in the 

 animals) is either of a pale yellowish- or olivaceo-corneous, or 

 else of a warm and clear reddish-brown. 



I am indebted to the Rev. E. B. Watson for making me a 

 most careful tracing of this noble Succinea from the original 

 plate which is given by Lesson ; and had there been any doubt 

 concerning the identification (which the extreme accuracy of 

 the outline renders impossible), it would at once have been dis- 

 pelled by the recorded habitat — ' dans les feuilles des Cabbage- 

 trees, ou Solidago, sur la montagne de Diana ' ; this particular 

 species being the only one, so far as I am aware, which ascends 

 to the highest points of the Diana-Peak ridge, — where, more- 

 over, as just stated, it literally abounds. 



Succinea picta. 



Succinea picta, Pfeiff., Proc. Zool. Soc. Lond. 133 (1849) 

 „ imperialis, Bens., Ann. Nat. Hist. 262 (1851) 

 „ picta, Pfeiff., Mon. Hel. iii. 12 (1853) 

 „ rudorina, Melliss [nee ' Gould '], St. Hel. 119 

 (1875) 



Habitat in locis similibus ac prgecedens, sed magis versus 

 occidentem insulas ; folia Compositarunn ad * High Peak ' de- 

 struens. 



I am in very great doubt whether this large Succinea should 

 be regarded in reality as anything more than a slight local 

 phasis of the S. Sanctce-Heleyice, peculiar to the more western 

 portions of the great central ridge,— -where on the foliage of the 

 Cabbage-trees which clothe the inner and precipitous slopes of 

 High Peak it does precisely the same work of destruction as 

 that species does in the direction of Diana's Peak and Actseon. 



