MADEIRAN GROUP. 87 



Patula placida. 



Helix piisilla (pars), Loive, Cambr. Phil. S. Trans, iv. 46. 

 (1831) 

 „ placida, ShuttL, Bern. Mitth. 140 (1852) 

 „ „ Pf eiff., Mon. Hel. ni. ^'2 {1^5^) 

 „ pusilla, /S. sericina, Loive, Proc.Zool. Soc. Lond. 176 



(1854) 

 „ Luseana, Paiva, Journ. de Conch, xiv. 342. pi. 11. 



f. 9 (1866) 

 „ „ Id., 3Ion. Moll. Mad. 80. t. 2. f. 3 (1867). 



Patula placida, Mouss., Faun. Mai. des Can. 25. pi. 2. 

 f. 9-12 (1872) 



Habitat Maderam ; sub cortice arborum, necnon inter muscos 

 licbenesque ad truiicos laurorum, in sylvaticis editioribus pne- 

 cipue gaudens. Semifossilis prope Canipal a Eevdo. R. B. Wat- 

 son, reperitur. 



This minute Patula formed a portion of Mr. Ijowe's H. pu- 

 silla (enunciated in 1831), and which in 1852 he separated 

 from the still smaller, browner, and more depressed examples 

 (the habits of which are different, and which have a tendency 

 to be sculptured with remote hair-like costae) as the ' var. /3. 

 sericina.'' In the meanwhile however it had been published by 

 Shuttleworth, under the name placida, from the Canarian 

 archipelago. 



I think there can be little doubt that the P. placida is 

 truly distinct from the smaller and less turbinate form which 

 constituted the type of the pusilla, Lowe ; and its mode of life, 

 too, is not the same, — for, whilst the pusilla (which possesses 

 a very wide geographical range) occurs principally under stones, 

 and within the hollows and crevices of scoriae, in dry spots of a 

 comparatively low elevation, the placi'la, on the other hand, is 

 attached normally to the sylvan districts of a higher altitude, 

 where it congregates beneath the bark of trees, as well as 

 amongst moss and lichen on the damp trunks of the old laurels. 

 Under such circumstances it is universal throughout the wooded 

 portions of Madeira proper, but it has not yet been observed in 

 any of the other islands of the Group, In the Canarian archi- 

 pelago it is equally common as at Madeira ; and I have myself 

 met with it in the forest regions of Teneriffe, Palma, and 

 Hierro. 



I may add that in Madeira the P. placida appears to be 

 found likewise in a subfossil condition, — the Rev. R. B. Watson 

 having informed me that he obtained it sparingly (along with 

 the true P. pygmoia, Drap.) in the calcareous deposits near 

 Canifal. 



