CANAR1AN GROUP. 479 



minor ' ; but it is singular that Mousson should have arrived 

 at the same conclusion, seeing that he had my own examples 

 from Las Mercedes and Taganana, which are quite as small, 

 and quite as obscurely coloured, as the Palman ones, under 

 his immediate eye. 



The larger (or typical) individuals of the H. gutta measure 

 about 1^ lines in length, and the smaller ones (or 'var. /3. 

 minor' 1 ) about 1 line. 



GASTROPODA (PECTINIBRANCHIATA). 



Fam. 12. RISSOID^E. 

 Genus 25. HYDROBIA, Hartm. 



Hydrobia Pleneri. 



Hydrobia Pleneri, Frauenf., Verh. d. Zool. Ges. Wien, 1024 



(1863) 

 „ „ Id., ibid. 526 t. 8. f. 4 (1865) 



„ „ Mouss., Faun. Mai. des Can. 148 



(1872) 



Habitat Teneriffam ; ad Eealejos, sec. mus. Cuming, lecta. 



This is a Hydrobia with which I am not acquainted; and 

 Mousson also appeared to have no knowledge of it beyond what 

 he was able to gather from the short published diagnosis. Whe- 

 ther therefore it be truly distinct from his H. canariensis, 

 which was detected by myself in Fuerteventura, and which is 

 likewise conical and quite imperforate, may perhaps be open to 

 enquiry. Frauenfeld's description of it is as follows: — 'T. 

 conoidea, tenuis, diaphana, oleaceo-grisea, lardeo-nitida. 

 Anfr. 6^, planiusculi, supra subdeclivis, sutura vix impressa. 

 Apertura elongata, infra valde producta, intus alba, supra 

 angulata. Columella tota arete adnata, sine rima umbilicari.' 

 ■ — Long. lin. 2^ ; diam. vix \\. 



Hydrobia canariensis. 



Hydrobia canariensis, Mouss., Faun. Mai. des Can. 148 



(1872) 



Habitat Fuerteventuram ; a meipso in cisterna, quadam 

 juxta oppidulum Sta. Maria Betancuria, inter plantas Typhce, 

 detecta. 



A few examples of a rather elongate and conical Hydrobia 

 which I met with in a Typha-crowded tank near Sta. Maria 

 Betancuria, the ancient capital of Fuerteventura, were described 



