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II. On some New Species of Nudibranchiate Mollmcafrom the Eastern Seas. 

 By Cuthbert Collingwood, M.A., M.B., F.Z.S., &c. 



(Plates IX. & X.) 



Read March 7th, 1878. 



THE very considerable numbers of naked-gilled Mollnsca which have been found 

 upon our own shores would lead one to suppose that on other coasts, in which climatal 

 conditions were more favourable, they would be very commonly met with. Having 

 collected not fewer than twenty-eight species upon a very small section of our northerly 



Wes'tof^r , H " T 1 '^ 1 SGarCh UP ° U tr ° piCal Sh ° reS W ° m ^ ld - a ^ant 

 haivest of these highly mterestmg and beautifully-tinted animals. In any such research 



however, seasonal changes must not be overlooked. There can be no doubt in the mini 



of any one who has ransacked tropical localities that in them the highest development 



o colour and he most curious vagaries of form are to be found ; but I am persuaded 



ha a zoologist who pays but a brief visit to a number of coasts in succession is far less 



likely to make a considerable collection of species of Nudibranchiata than is anyone 



who, confined to a single favourable locality for a considerable period, is thus able to 



pursue h* examination of the same spot through all the different seasons of the year 



Hence it is that the collections of Sir W. Elliot on the Madras coast (32 species), of 



1 1. Kelaar on the Ceylon coast (42 species), and of Mr. Angas in New Smith Wales 



hat'ofT^T S ° laV§ V^!f Q the V °^ e ° f thG ' Asteolabe ' y^d but 18 new species, 

 that of the Samarang half a dozen species, and my own researches (the fruits of eve™ 

 opportunity within my reach during a period of rather more than twelve months) resulted 

 only m the discovery of the 16 new species described in the following paper 



The greater number of species of this group may be found upon stony shores near low- 

 water mark, and especially at low spring-tide. They adhere to the under side of stones 



labW l ^ tlU ' Uing tLem 0Ver " Alth ° U - h SOme of them a PP<*r to be 



capable of swimming, and most of them can float, branchiae downwards, upon the surface 



ol the water I never saw them in this position in the sea, however calm. In fact the Y 



have invariably been found by me in a passive condition, like little shapeless masses of 



oft, coloured matter, in depressions and crevices of stones, where they have probably 



retired at that particular juncture, when the wash of low tide has disturbed the water 



and rendered it both turbulent and turbid; from both of which disadvantages the same 



spot would be free at all times, except at dead low-water. I have, however, dredged up 



a very beautifully-eolourecl and delicate species from a depth of 20 fathoms, which 



notwithstanding the rough handling of the dredge and the company of shells, corallines' 



and sponges, seemed in no way incommoded or less lively. Again, some species of 



JNudibranchiata, as Glaucus, appear to be free ocean-swimmers, and such I have taken 



the towmg-net m the Formosa channel; while another species {Scyllcea pelagica) is 



SECOND SERIES.— ZOOLOGY, VOL. II. 17 



