of British Mollusca . 339 
que j’ai recueillie en Algerie. C’est dans la collection de cct 
amateur que Pfeiffer la vit et la decrivit.’ ” 
254. Succinea oblonga , Draparnaud. 
B. Ditremata. 
Fam. 7. Oncidiidge. 
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 Oncidiidae has been much 
disputed. Bergh *, after reviewing the varied opinions of 
authors, sums up his views thus : — u The Onchidia agree with 
the Pulmonata 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 amphibiotic or 
marine mode of life.” 
Suborder II. GEIIYDROPHILA. 
Fam. 8. Auriculidse. 
Genus 1. Carychium, O. F. Muller. 
256. Carychium minimum , Mull. 
Genus 2. Alexia, Leach. 
257. Alexia myosotis (Drap.). 
258. Alexia denticulata (Mont.) = Melampus myosotis , var. 
ringens , Jeffr. 
Genus 3. Leuconia, Gray. 
259. Leuconia bidentata (Mont.). 
Yar. alba , Turton. 
* Bergh , 1 Morphologisches Jahrbuch,’ Bd. x. p. 172; translated, Ann. 
& Mag, Nat. Hist, ser, 5, xiv. 1884, p. 259. 
