478 TESTACEA ATLAXTICA. 



Hydrocaena Grutta, Drouet, Faun. Acor. 170 (1861) 



Mouse., Faun. Mai. des Can. 147 (1872) 



Habitat Teneriffam, et Palmam ; in locis valde humidis, saepe 

 etiam subaquosis, et praecipue sylvaticis, occurrens. Ad rupes 

 praeruptas udas, supra oppidulum Grarachico TenerifFse, abun- 

 dat, una cum Hyalina Glymene, Pupa castanea, Physa 

 acuta, et Ancylus striatus consociata ; et nunquam (nisi fallor) 

 in aridis, ut ait clariss. Mousson, degit. 



This extremely minute, Paludina-like shell, which occurs 

 also in the Azorean archipelago but which has not yet been ob- 

 served at the Madeiras, will most likely be found eventually to 

 be widely spread over the Canarian Group, although hitherto it 

 has not been observed except in Teneriffe and Palrna. I have 

 myself, however, met with it abundantly in both of those islands, 

 namely amongst the detritus about the roots of ferns, as well 

 as by beating their fronds, on some damp rocks in the wood of 

 Las Mercedes, of the former, within the constant douche of the 

 spray of a waterfall, and likewise in a somewhat similar situa- 

 tion at the edges of the Vueltas above Taganana ; whilst in 

 Palma my specimens were principally obtained, in the same 

 kind of moist places, in the Barranco de Gralga. Mousson has 

 consequently fallen into an unaccountable error in citing it as 

 living ' sous les pierres arides,' and (again) ' sous les pierres 

 dans les lieux arides,' for nothing could possibly be more untrue 

 to its modus vivendi. Indeed he has himself (however unwit- 

 tingly) settled the question as to its real habitat in the same 

 actual sentence ; for he expressly mentions that it was found in 

 company with the Hyalina Clymene and the Pupa castanea, 

 and the only spot in which the former has hitherto occurred 

 (and I believe, also, the latter) is some trickling rocks, adjoin- 

 ing a small waterfall, above Grarachico, in the north of Teneriffe. 

 Indeed that is the original locality from whence Blauner's ex- 

 amples, subsequently described by Shuttleworth, were brought ; 

 and the latter particularly notes that they were taken ' sub saxis 

 udis in Teneriffa.' 



Apart from its diminutive bulk and imperforate shell, the 

 H. gutta may be known by its comparative freedom from sculp- 

 ture (the minute lines of growth being often very obscure) and 

 its only slightly shining surface. The examples from the neigh- 

 bourhood of G-arachico, which (as being the ones which were 

 described by Shuttleworth) must be regarded as typical, are 

 larger and of a more reddish-yellow tinge than those (the ' var. 

 (3. minor ') from the higher altitudes of both Teneriffe and 

 Palma. Shuttleworth having no other Teneriffan specimens to 

 judge from except those from the vicinity of Grarachico, natu- 

 rally regarded the Palman ones only as representing his 4 var. 



