marine British Shells and Animals: 183 
BULLA. 
It has been long known that one of the Linnæan species of this 
genus of Testacea, instead of being the external covering of the 
animal to which it is attached, is concealed within. The Bulla 
aperta is so completely concealed by its animal, that there is 
not the smallest appearance of it : dissection, therefore, probably 
brought it first to light. The animal has been distinctly de- 
scribed by several authors under different names, and lastly by 
Muller under the title of Lobaria quadrilobata. 
In Testacea Britannica two other species of Bulla have been. 
| given, whose nature it is to be concealed by the animals to which 
they belong ; and since the publication of the Supplement to that 
work, two other species of a similar nature have occurred. that 
appear to be undescribed. These four possess characters suffi- 
ciently similar to determine them to be of the same genus; but, as 
they cannot be arranged with Lobaria nor any other genus.in the 
divisions of Vermes, Mollusca or Testacea, I have thought it pro- 
per to form these animals into a new genus, under the title of 
Lamellaria. 
The animals of this genus are more nearly allied to Aplysia in. 
some particulars than to Lobaria, to which they are only con- 
 mnected by being testaceous Vermes ; but they differ from the 
former in not having reflected membranes, and in the shell being 
testaceous, and spirally formed at one end, which in that is cor- 
. neous and destitute of convolution. From Lobaria they also dif- 
fer in being formed of two fleshy laminz, and not into lobes or 
lateral divisions. It is not improbable that some species of La- 
mellaria might be mistaken for Dorides, but there are sufficient 
distinguishing characters obvious to the Helminthologist. 
There appear to be two natural divisions in this genus of 
: : Vermes, 
