Land, Fresh- Water, and Marine Crustacea. 97 



XIV. A Catalogue of Land, Fresh- Water, and Marine Crustacea 

 found in the Basin of the River Forth and its Estuary. 

 By Thomas Scott, LL.D., F.L.S., Mem. Soc. Zool. de 

 France, etc. [With Map. Plate VI.] 



(Read 27th March 1905.) 



PAKT I— MALACOSTEACA, CLADOCERA, and 

 BRANCHIUEA. 



Introductory Eemarks. 



(1) On the Drainage Area of the Forth} 



The river Forth, from its source on the side of Ben 

 Lomond to where it terminates in the estuary near 

 Kincardine-on-Forth, measures about 64J miles, and as the 

 length of the estuary is about 48 miles, the total length, 

 from the source of the river to the seaward limits of the 

 estuary, is slightly over 112 miles. Leslie and Herdman 

 describe the Forth estuary as extending to the Vale of 

 Stirling, or about 8 miles farther west than the limit 

 stated here. 



The drainage area of the river, including its tributaries, is 

 almost 628 square miles, while that of the estuary is about 

 1133 square miles, or about 1760 square miles altogether. 



The average depth of the estuary scarcely exceeds 15 

 fathoms. There are one or two places where it reaches 

 to about 40 fathoms, but these are very limited. A con- 

 siderable portion of the estuary towards its seaward limits 

 ranges from 15 to 30 fathoms in depth; but nowhere is 

 there such deep water as in the Firth of Clyde. 



The largest fresh -water lochs within the area are — Loch 

 Katrine, Loch Vennachar, Loch Voil, Loch Lubnaig, and 

 Loch Leven (Kinross). There are a number of smaller 

 lakes, such as Loch Achray, Loch Ard, Lake of Menteith, 

 and others, a few of which, though not yet examined, are 



^ The measurements, etc., given here are obtained chiefly from Part II. 

 of the Tioelfth Annual Report of the Fishery Board for Scotland (1894), 

 which contains a map of the catchment-basins of all the Scottish rivers, 

 with explanatory notes, giving the lengths of the various rivers, the areas 

 of each river-basin, and other useful information derived from official sources. 

 VOL. XVI. M 



