of British Mollusca. 339 



que j'ai recueillle en Algerie. C'est dans la collection de cet 

 amateur que Pfeiffer la vit et la ddcrivit.' " 



254. Saccinea ohlonga, Draparnaud. 



B. D I T E E M A T A. 



Fam. 7. Oncidiidse. 



Genus Oncidiella, Gray. 



255. Oncidiella celtica (Cuvier). 



The young of this species in its larval state is furnished 

 with a shell which is afterwards cast off. 



The systematic position of the Oncidiidse has been much 

 disputed. Bergh *, after reviewing the varied opinions of 

 authors, sums up his views thus : — ^'The Onchidia agree loith 

 the Pulmoriata in the structure of the nervous system, in the 

 existence of a lung and of a parenchymatous kidney, in the 

 presence of the peculiar pedal gland, and in various peculia- 

 rities of the generative system. From a tolerably extensive 

 knowledge of the so-called Nudibranchs I cannot but regard 

 the Onchidia as pretty widely separated from them. On the 

 contrary, they branch off from the Pulmonata ; they are Pul- 

 monata which have adapted themselves to an amphihiotic or 

 marine mode of lifer 



Suborder II. GEHYDROPHILA. 



Fam. 8. Auriculidge. 

 Genus 1. Caeychium, 0. F. Miiller. 



256. Carychium minimum, Miill. 



Genus 2. Alexia, Leach. 



257. Alexia myosotis (Drap.). 



258. Alexia denticulata (JAo\\{.) — Melam2nis myosotis, var. 

 ringens, Jeffr. 



Genus 3. Leuconia, Gray. 



259. Leuconia hidentata (Mont.). 



Var. alba, Turton. 



* Bergh, 'Morphologisches Jahrbuch,' Bd. x. p. 172; translated, Aim. 

 & Mag. Nat. Hist. sor. 5, siv. 1884, p. 259. 



