22 4 Proceedings of the Royal Irish Academy. 



produced no less than 133 species. This last was the richest yield of any 

 single haul made in the area, and has, I think, heen rarely exceeded by any 

 single haul made in Irish coastal waters. In a large proportion of the total 

 of 28 effective hauls made by the " Helga " during her three visits the tow-net 

 was used attached to the dredge, so as to secure samples of the finer material. 



The inshore or shallow-water dredgings were made usually from a row- 

 boat or small sailing-boat or from a pookaun, the stout lug-sailed craft by 

 which eomnrunieation is carried on between Clare Island and the mainland. 

 A total of 24 productive dredgings were made, and in the majority of these I 

 was assisted by Mr. Praeger. In July, 1909, five scrapes were made at Clare 

 Island, one in about 12 fathoms off the Light-house Cove, and four in about 

 5 fathoms off the harbour or off Granuaile's Castle. On the 26th of the same 

 month Mr. A. D. Cotton joined me in a dredging-trip by sailing-boat amongst 

 the inner islands of the bay from Eossmindle by Sruhnamael (Maelstrom) 

 round Inishlyre and Collon Beg, when four productive hauls were made in 

 from 2 to 5 fathoms. In May, 1910, twelve hauls were made in the Westport 

 Channel, nine of these off Scotch Bonnet and Inishiiumel and three in Inishlyre 

 Boads : and finally in July of the same year, three hauls were made at Clare 

 Island, two of them off the Castle in about 5 fathoms, and the third within 

 half a mile of Light-house Cove in about 10 fathoms. This last haul proved 

 a rich one, yielding me a total of 104 species. All of these inshore dredgings 

 were made with a close-meshed dredge-bag which retained much of the finer 

 material. 



Altogether 52 effective dredgings were made within the area, the " Helga's " 

 23 deep-water haids being so distributed as to yield samples from all parts 

 of the open bay, while the shallow-water dredgings, like the shore-gatherings, 

 were almost confined to the Clare Island shores and the neighbourhood of 

 TYestport Bay and channel. 



III. The Molluscan Fauna. 



I Its Extent, Constitution, and local Distribution. 

 The survey operations just described, incomplete though they were, have 

 vielded material sufficient to serve as foundation, not only for what is the first 

 detailed list of the Marine Mollusca of Clew Bay, but also for a first attempt 

 to estimate the relative frequency of the various species. The bay was visited 

 and dredgings made there about the middle of the last century by many able 

 and zealous workers, such as Edward Forbes, Bobert Ball, William Thompson, 

 and Dr. Farran. But the only published results of their labours in the 

 district are a few scattered records in various works, yielding a total of no 

 more than 19 species. 



