DREDGING- OFF FORTINCROSS, AYRSHIRE. 191 



most impalpable kind. Never but once, when dredg- 

 ing off the mouth of Loch Broom, Ross-shire, had so 

 little debris remained in the sieves after dipping 

 them at the boat's side. One of our number had 

 brought fine muslin bags in which to wash the 

 dredgings for Ostracoda and Foraminif era ; but the 

 impalpable material, which must have been very 

 barren of the minuter forms of life, almost entirely 

 disappeared through the muslin mesh. 



Our special object in the expedition was to gain 

 some idea of the Mollusca of the locality. The 

 siftings obtained during the day, which amounted 

 to no more than a few ounces, were roughly 

 examined at the time for the larger forms, and then 

 the material was carefully bagged for after-examina- 

 tion, as it is profitless expenditure of time to 

 attempt the picking out of minute species from wet 

 sieves. The siftings have since been carefully gone 

 over, first by myself, and then by Mr. J. T. Marshall, 

 of Torquay, so that probably nothing has escaped 

 notice. The interest of the day's work may be said 

 to have centred in two species obtained, viz., Rissoa 

 abyssicola, Forbes, and Pleurotoma hr achy stoma, 

 Philippi; and I have the authority of Mr. David 

 Robertson, our President, for saying that the former, 

 so far as he is aware, is new to the eastern side of 

 the Firth, and that the latter has not previously 

 been recorded alive from the Clyde. R. abyssicola 

 was discovered and named by the late Professor 

 Edward Forbes, who, with Mr. M'Andrew, dredged 

 it in Loch Fyne, where I also met with it last 

 summer in 50 and 75-fathom water. Its habitat is 

 an undisturbed muddy bottom at considerable depth, 

 and I may say that I have taken it in Gairloch and 

 Loch Broom, Ross-shire, in Loch Hourn, and between 

 the Islands of Eigg and Rum, at all which places 

 these conditions prevail. Nowhere, however, have I 

 in one day taken so many examples as here, for, at 

 the two depths, and between good, indifferent, and 

 bad specimens, over 25 in all were obtained. None, 



