NOTES ON THE MAEIXE MOLLUSCA OF POET-STEWART. 13 



shells are therein myriads, just above high-water mark, and 

 therefore able to abide calmly the wrath of the billows of 

 the Atlantic. A higher wave than usual may sweep over 

 them, but as a rule they are smitten merely by the flying 

 spray, and thus their position on these truncated columns is 

 apparently as secure as is "Lord Antrim's Chair." Mr. 

 Brown admitted this species into his Clyde list under 

 protest, and solely on the authority of Canon Norman, who 

 affirmed that he had obtained it in abundance on the Outer 

 Allans, at Millport. Neither Mr. Brown nor Dr. Robertson 

 had ever this good fortune. But since the date of Brown's 

 list it has been secured in several other places on the Clyde, 

 and its establishment as a record is certain. In a letter 

 which I received from Canon Norman in July last, he stated, 

 "All I can say is that specimens taken in 185-1 are still in 

 my collection, and that the last time I was at Cumbrae, in 

 1888, I found it in another spot — Farland Point." 



*L. rudis {Maton.). — In its usual abundance. 



*L. littorea (L.). — Everywhere plentiful. 

 Rissoa2)arva {Da C). — A solitary example of this very common 



species. 

 R. striata {Ad.). — A single specimen of this equally common 

 species. 



*R. cingillus {Mont.). — Two specimens. 



*IIydrohia ulvce {Penn.).—A few examples from the sands ; not 

 plentiful, as the mud which it loves is absent from the 

 neighbourhood. 



[*//. jenkinsi, E. A. Smith.. — I obtained two specimens of this 

 most interesting species, both from the tide marks on the 

 sands of Port-Stewart. It is a moot point whether this 

 shell should be regarded as purely a fresh-water mollusc, but 

 until the question is definitely settled we may treat it here 

 as at least a brackish-water species. The history of the 

 mollusc is peculiar. In October, 1889, Mr. Edgar A. Smith, 

 Keeper of the MoUuscan Collection in the British Museum, 

 described in the Journal of Conchology an apparently new 

 species of Hydrobia, which Mr. A. J. Jenkins had collected 

 on Plumstead Marshes. Specimens of a similar character 

 were also forwarded him from ditches at Beeton, near North 



