196 Dr. C. Collingwood on the Nudibranchiate Mollusca 
grooves extending to the edge of the foot, these grooves being 
opposite to each other at their origin. 
As I believe the animal has not yet had a name applied 
to it, I would suggest that it should be called, in recollection 
of the island where it was first discovered, and also of its first 
discoverer, Aneitea Macdonaldii; and the observations above 
given will form its generic character. In other characters it 
agrees with Limaz. 
I may add that the description and figures of the tongue and 
teeth of Janella given in the interesting paper of Mr. Knight show 
that Janella forms a most distinct family of terrestrial Mollusks. 
Mr. Knight observes that he has termed the covering of the 
whole upper surface of Janella “the mantle,” in deference to my 
views ; but he thinks that it ought “more probably to be regarded 
as quite naked.” The study of the genus Aneitea and the exa- 
mination of Mr. Knight’s paper have induced me to change my 
views. I now believe that the mantle is confined to the upper 
surface of the small respiratory cavity of both these animals ; 
and this is confirmed by Mr. Knight having discovered “ four 
small semitransparent calcareous (?) granules in the anterior 
wall of the pulmonary sac,” showing that this part must be a 
“secretory organ ;” but I do not understand how animals 
having such plates can be “regarded as quite naked.” 
XXIX.—On the Nudibranchiate Mollusca inhabiting the Estuary 
of the Dee. By Curusert Cotiinewoon, M.B., F.L.S. &c.* 
In a former paper I described the species of Nudibranchiata 
which up to that time had become known to me as inhabiting 
the estuary of the Mersey ; I propose in the present communi- 
cation to make some remarks upon those which are found in the 
neighbouring estuary of the Dee. I will not here dwell upon 
the species which are common to both rivers, having already 
made special reference to them as existing in the Mersey, while 
the table at the end of this article will sufficiently indicate their 
comparative rarity or profusion in both situations. The Mersey 
species which have not hitherto been detected im the Dee are 
Embletonia pallida, peculiar to the Mersey, and Holis concinna 
and E. despecta. Of these, Hmbletonia has not been taken for some 
years ; and it is to be feared that the locality in which Mr. Price 
first discovered it has been destroyed by the formation of the 
Birkenhead Docks. During the past spring, I have found a 
third small species of Zolis in the Mersey at Egremont, in com- 
* Communicated by the author, having been read before the British 
Association at its Meeting at Oxford (1860). 
