BULLID. 273 
M. Lovén, 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 imvestigation 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. Lovén’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 Bulle. 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 Bulle 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 Bullide ; 
it is possible those parts m so mimute 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 1s synonymous with Bulla, 
T 
