Experiments on the Respiration of Melamjms. 287 



be drawn from the preceding experiments, on the other side. Yet it 

 may not be amiss briefly to recapitulate them, putting against each its 

 contradictions, to set the matter in its clearest light. 



The arguments tending to prove Melampus to belong to the Pulmonea 

 or air-breathing MoUusca, are, 



1. The habits of Mel. aqualis (Experiments 1 and 2.) are not what 

 we should imagine to be those of a marine Pectinibranchia, living 

 habitually in water. 



Rendered inconclusive by the habits of Lillorina vulgaris and other 

 littoral MoUusca, decided Pectinibranchia, which are exactly the same. 

 And Melampus exigmis has not these habits (Experiments 6, 6.) but re- 

 mains at the bottom of the water. 



2. Its surviving for six weeks in a box without water (Experiment 4.) 

 But it was in wet sponge ; and besides, Littorina vulgaris, in the 



same box, did also survive. At all events, the anomaly is not greater 

 than in the case of Truncatella truncatula. See Experiments 16 and 17. 



3. Its not living more than 3 — 4 days immersed in sea-water. 

 Surely 3 — 4 days are enough, comparing it with the time that a Helix 



survives (see the two preceding notes ;) but if not, seven out of eight 

 specimens of Pedipes afra (a decided Pectinibranchia) survived no 

 longer ; the eighth lived two months immersed ! 



4. Its pectinated branchice are not visible. 



But the small size of the species, not to mention want of instruments 

 and skill in the dissector, sufficiently explains this. 



5. The presence of the bubble of air at the mouth of the orifice in 

 the mantle, &c. 



This is caused only by the air accidentally received into the cavity of 

 the shell, and amongst the branchice, when the animal has been some time 

 out of the water ; and besides, in Melampus exiguus, it is not constant ; 

 compare Experiments 6 and 7 with 5. 



The following are the recent species which appear to unite generically 

 under Melampus as above defined. 



