196 Mr. MoxTAGv's Account of some new and rare 
- This is another Zetlandic production discovered by Mr. Fle- 
ming, who assures me that it is not uncommon on stones in deep 
water, and was first noticed on the stones attached to the cod- 
lines which bad lain long under water. The colour is invariably 
brown, as well on the inside as without ; and w ‚hen examined by 
a glass appears papillous. 
The largest specimens are about half an inch in diameter. 
VERMES MOLLUSCA. Ra cr 
Doris. | 
Since the writings of Linneus, it is not surprising that the 
rapid cultivation of the science of Natural History should have 
extended the field so greatly : as to call for some new arrangements 
in this branch as well as in all the others. It is true that with 
‘some alterations in the leading characters of the Linn&an genera, 
many of the more recently discovered animals might still have 
found a place in the arrangement of that great naturalist: but 
systematic physiologists are as verbally tenacious as lawyers; 
and therefore, where the generic characters do not exactly apply 
to the object, a new genus is formed for the purpose. It appears 
that the genus under consideration admits of three or four natu- 
ral divisions ; and, as the number in this genus is not very exten- 
sive, such a division into families might have answered all the 
purposes of identifying species, without too greatly multiplying 
genera, which in the end will frustrate the intention of systematic 
arrangement. > 
It must be acknowledged that these are several animals arranged 
with the Gmelinean Doris, which want the essential Linnean cha- 
racters of that genus : for instance, Doris clavigera is destitute of 
vent on the back surrounded by a fringe. This, therefore, (as 
well 
