128 DXTBLIN NATUEAL HISTORY SOCIETT. 



PfiOFEssoR KiNAHAN, M. D., F. L. S., read — 



NOTES ON DEEDGING IN BELFAST BAY, WITH A LIST OF SPECIES. 



In a communication entitled " On Xantho rivulosa and other Deca- 

 podous Crustacea, occurring at Yalentia Island, county of Kerry" {vide 

 "Proceedings Dublin Natural History Society," vol. ii., pp. 16 and 33 ; and 

 ante, vol. iv., "Proceedings of Society," pp. 69 and 86), laid before your 

 Society in 1856, I remarked on the fact that of the peculiar species 

 found on the west coast, several were not met with on the Dublin 

 shores, yet are common in the northern portions of the eastern coasts 

 of Ireland ; and, founded on this, I suggested that it appeared probable 

 that a portion of this stream of western and southern species would seem 

 to have, as it were, overlapped the northern portion of the island, and 

 to have died out before reaching the Dublin, or, as I called it, the pro- 

 per eastern district. An examination of Belfast and Carrickfergus Bays 

 during the past summer, whilst affording me several previously unnoticed 

 Crustacea, has furnished me with additional proofs of this. 



I allude to this theory the more particularly, because I learn that re- 

 cently doubt has been expressed as to a similar distribution among the 

 shells ; and facts adduced by Messrs. HjTidman, Patterson, Waller, and 

 Dickie, attempted to be explained away by supposing either that the 

 southern and western types, quoted by those gentlemen, owed their pre- 

 sence here and in the list to pleistocene deposits, ocean currents, or pos- 

 sibly, as was also suggested, to some " Irish blunder." Now, as regards 

 this latter, it ought to be sufficient that all the critical species had been 

 identified by Alder, Gwyn Jeffreys, and other men of note on the other 

 side of the Channel ; and one of the species in dispute, Odostomia con- 

 spicua, was named by its first discoverer in England, Mr. Alder; and if 

 the objectors, instead of so readily prejudging the matter, had taken the 

 trouble to cross the Channel, even a few days spent at Galway and Bel- 

 fast would soon have satisfied them that as regards the common typical 

 shells of the two ports, several in the latter places were much commoner 

 and more typical there than further south-east, being in fact either 

 South British or Lusitanian. 



Tapes aurea, for instance, common in the west, not uncommon in 

 Belfast, is unknown, as far as I can learn, in Dublin. Mactra subtrun- 

 cata^ rare in Dublin, common in the west, is also extremely common in 

 Belfast. Trochus magus, a common littoral species in the west, un- 

 known as such, as far as I can learn, in Dublin, is by no means rare as 

 a littoral species in Carrickfergus. But it would consume too much 

 time were I to notice all the species which illustrate this point ; and 

 there is not the slightest cause for wonder that such shells as Chemniizia 

 scalar is, Ovula patula, Adeorhis suhcarinata, and Hissoa striatula, have 

 occun-ed to the Belfast Dredging Committee. 



The distribution of the Crustacea affords data confirmatory of this ; 

 and Dr. E. Percival "Wright, in a recent paper of his on Irish Actinia, 

 has noticed the same point ; and there appears to be little doubt that 

 when the other sections of zoology shall have been accurately studied, the 



