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M. Loven, amongst them Cylichna and Amphisphyra, but the 

 minuter species are so rarely met with alive, that they can 

 scarcely be placed with certainty ; and to add to the difficulty, 

 the excellent Loven, one of the most careful observers, has I 

 think fallen into some error with respect to the genus Cylichna, 

 the generic diagnoses of which would appear, from our present 

 notes on two of the species he has deposited therein, the 

 B. cylindracea and B. truncata, not to be founded on correct 

 bases. But what naturalist does not sometimes fail in his 

 views, from various causes, especially in the investigation of 

 the difficult tribes of the minuter animals ? 



I propose to show that the B. cylindracea and B. truncata 

 are congeneric with B. hydatis ; if this be so, I may further 

 observe, that on analogical considerations it is extremely 

 probable that M. Loven' s B. umbilicata, which is also one of 

 our indigena, is in the same category as to error, and, with 

 our B. obtusa and B. mammillata, not yet I believe observed, 

 will turn out to be strict Bulks. Until these minute creatures 

 have been submitted to fresh examinations, this family cannot 

 be settled; no conchological considerations will suffice. It 

 may be that the unobserved species will afford valid generic 

 distinction ; but I think, from the constancy of structure of 

 all the Bulla that have been adequately observed, they will, 

 though the presumption rests on analogical grounds, be found 

 to have the tripartite gizzard and typical foot with its accessory 

 lobe extending from one extremity of the animal to the other, 

 with the sides more or less reflexed, producing the quadri- 

 lobated character of the tribe. 



I can say little of the genus Amphisphyra ; the only British 

 species, the B. hyalina, is not found on our southern coasts, 

 and the notices of it are so meagre, that at present it can only 

 be placed provisionally. It has been stated to have neither 

 gizzard nor head-disc ; if so, it cannot belong to the Bullida ; 

 it is possible those parts in so minute a being may have 

 escaped detection, and it may prove to be a Bulla. Naturalists 

 residing near the locality of this species should re-examine 

 these points and communicate their notes. 



The Scaphander of Montfort is synonymous with Bulla, 



T 



