Mr. C. Collingwood on Nudibranchiate Mollusca. 461 



directed to the subject and search were made ; and it can only 

 be owing to the comparative rarity of the little creatures that 

 they have not been observed before * " 



EXPLANATION OF PLATE XVIL 



Fig. 1. One of the young Madrepores, on Oct. 6th, 1850^ seen from above ; 

 nat. size. 



Fig. 2. The same, on Oct. 6th. 



Fig. 3. The same dividing, Oct. 7th. 



Fig. 4. The same divided, and ready to divide again, Oct. 9th. 



Fig. 5. The right-hand moiety, on the same date, viewed in perspective. 



F^gs. 6, 7' The same moiety, Oct. 12th, now become two, viewed in dif- 

 ferent conditions ; about twice the nat. size. 



Fig. 8. The larger of the last division, Oct. 25th, showing the development 

 of new tentacula (expressed by the inner circle of dots) ; twice 

 nat. size. 



Fig. 9. Threefold division of one specimen, June 15th, 1851. 



Fig. 10. A specimen attached to two pieces of rock, June 25th. 



Fig. U. Another, with a young one developing by gemmation from its 

 upturned base, June 27th. 



[Mrs. Thynne wishes it to be understood that the figures are not finished 

 drawings, but slight outlines made to assist memory ; correct, however, 

 though rough.] 



XLV. — The Estuary of the Merseij considered as a Locality for 

 Nudibranchiate Mollusca. By Cuthbert Collingwood, 

 M.A., F.L.S., &c. 



Although every district has its variety of natural productions, 

 whether terrestrial, fluviatile, or marine, still there is usually 

 some family which predominates in each locality, giving it a 

 peculiar character, and in which it may be regarded as, at least 

 comparatively, rich. 



The marine fauna of Liverpool is by no means destitute of 

 interest in other families, and possesses an ample share of 

 zoophytal productions in particular ; but it is more especially in 

 the Nudibranchiate Mollusca that its riches appear. Of this 

 remarkable and lovely family it may be said to possess more 

 than an average share, including some of unusual interest. The 

 present paper will only take cognizance of the Mersey mouth and 

 estuary ; but by extending our researches to the neighbouring 

 estuary of the Dee, we find within ten miles of us fresh rarities 

 and beauties. It must also be taken into consideration that 



* And yet at this time (1859) hundreds, perhaps even thousands, of 

 individuals of Caryophyllia Smithii are taken annually by the Torquay and 

 Ilfracombe collectors, of various sizes and colours, while not a single 

 example has been found without a corallum. — P. H. G. 



