200 Dr. C. Collingwood on the Nudibranchiate Mollusca 



in the fact that these specimens were placed in a shallow glass 

 dish, and in a situation constantly exposed to draughts of fresh 

 air, which kept the water well aerated. 



The five species of Nudibranchiata which have been met with 

 in the Dee only, and not in the Mersey, are the following : — 



1. Doris depressa. This scarce little Doris, remarkable for 

 the great relative size of the spicula, was once taken by Mr. 

 Byerley at Hilbre Island. 



2. Doris subquadrata. Only two specimens of this rare Doris 

 appear to have been yet seen. The first was discovered by Mr. 

 Alder, in deepish water at Torbay, in 1845 ; and the second was 

 found by Mr. Byerley at Caldy Blacks, in the Dee. This spe- 

 cimen was forwarded to Mr. Alder, who confirmed the fact of 

 its being D. subquadrata. I believe it has never been taken 

 since. It was in company with Doris pilosa, to which species it 

 is closely allied, but yet differs from it in several points, and 

 particularly in the degree of development of the pallium, which 

 in D. subquadrata is so scant as to leave the head and posterior 

 part of the foot uncovered, when the animal is extended. 



3. The third peculiar Dee species is the Eolis olivacea. 

 The last excursion of the Liverpool Naturalists' Field Club 

 was to Hilbre Island, on which occasion, notwithstanding that 

 the day was hopelessly wet, it was not sufficiently so to damp 

 the ardour of ninety-five members and friends of this flourishing 

 Club. A few only landed ; but among the captures I was glad 

 to number Clavellina lepadiformis, new to our local list of Tuni- 

 cata, while, among some Zoophytes brought from the island by 

 Dr. Edwards, there appeared a specimen of the above Eolis not 

 hitherto known in this locality. It was a small specimen, very 

 brilliantly coloured, and altogether a very elegant addition to 

 our fauna. 



4 & 5. But the most interesting genus of all is perhaps that to 

 which the remaining two species belong. I refer to Antiopa, the 

 history of which is not a little remarkable. In 1844, M. Verany 

 of Genoa described a species of Nudibranch inhabiting the 

 shores of Southern Europe, under the name of Janus Spinolce. 

 The name Janus, however, having been already occupied by a 

 genus of Hymenopterous insects, Messrs. Alder and Hancock 

 proposed to call it Antiopa, in order to avoid confusion of ge- 

 neric terms. The animal in question appeared to approach very 

 near in its characters to Proctonotus mucroniferus ; but a re- 

 markable crest between the dorsal tentacles, added to the lamel- 

 lated form of the tentacles, and the terminal branching of the 

 biliary cells of the papillae, appeared to warrant its separation 

 from the genus Proctonotus ; and for seven years it constituted 

 the sole species of the genus, under the name of Antiopa splen- 



