320 TRANSACTIONS, NATURAL HISTORY SOCIETY OF GLASGOW. 



When working at considerable depths and on a 

 soft bottom, an ordinary dredge will be found of 

 little service, owing to the fact that it sinks in the 

 mud and fills almost immediately. This difficulty is 

 to a great extent overcome by the use of a light 

 trawl which can skim rapidly over the oozy surface. 

 The one we used had a breadth of beam of seven 

 feet, and was fitted with a net of the ordinary 

 "shrimiD mesh." By means of this, many of the 

 quick-swimming Crustacea, which usually escape the 

 dredge, Avill be taken in abundance. The method 

 first adoiDted by Mr. Murray on board the "^Challen- 

 ger," of fixing one or more tow-nets to the beam of 

 the trawl, is also of service, especially for capturing 

 the smaller Schizopods and Cumacea, though of 

 course it is impossible to determine the exact depth 

 at which they entered the net. 



The crustacean fauna of the Clyde, as comj)ared 

 with that of the Forth, offers some points of 

 interest. In the first jDlace we must note the appar- 

 ent total absence of several species from the latter 

 district, as Portunus arcuatus, Eupagiirus Prid- 

 eauxn, Pihiiniius hirtellus, Palinurus homarus, Cran- 

 gon sculptus, C. echinulattis, Nika edulis, and Pasiphaea 

 sivado. Several species met witli in shallow water 

 in the Clyde, and at no great distance from land, 

 as Inachus dorsettensis, Lithodes maia, Ehalia 

 Cranchiiy and Eurynortie aspera, occur in the Forth 

 at the mouth of the estuary beyond the Isle of 

 May, and the majority of the specimens taken come 

 from the deep-sea lines of the fishermen. It must, 

 however, be borne in mind that with the single 

 exception of a small spot near Queensferry, the 

 depth in the Firth of Forth j)roper nowhere reaches 

 forty fathoms, nor do we meet with this depth till we 

 have passed a considerable distance beyond the Isle 

 of May or seaward limit. On the so-called oyster- 

 banks the following species are commonly met with : 

 SteiiorhyncJius lostratus, Porcellana longicormSf 

 Galathea dispersa, Portu7ius depiirator, P. holsatus. 



