156 



Part III. — Seventeenth Annual Report 



Loch Acbray is the only loch of the present series where Diaptomus 

 wierzejskii was obtained. Lathonura reetirostris and the equally rare 

 Monospilus were also obtained here. Fifty species of Entomostraca and 

 four of Mollusca are recorded in this Table. The Entomostraca comprise 

 seventeen species of Copepoda, nine species of Ostracoda, and twenty-four 

 species of Cladocera. The formula shows the number of species belonging 

 to each group that were observed in each of the four gatherings. Co., 

 Copepoda ; Os., Ostracoda ; CI., Cladocera. 



Dates. 



Sept. 10, 

 1897. 



Nov. 27, 

 1897. 



March 17, 

 1898. 



June 28. 

 1898. 



Names of the groups, - 



Co. Os. CI. 



Co. Os. CI. 



Co. Os. CI. 



Co. Os. CI. 



Number of Species in each group, 



7, 2, 12. 



13, 8, 15. 



8, 4, 3. 



12, 4, 12. 



Number of Species in each gathering, 



21. 



36. 



15. 



28. 



! 



The largest number of species was obtained in the November gathering, 

 and the smallest in that collected in March. During my visi^ to the loch 

 in June the boatman who was assisting me drew my attention to a green 

 substance which he had observed growing in several places near the north 

 shore where the water was shallow. This proved to be a fresh-water 

 sponge (Spongilla fiuviatilis). It appeared to be moderately common in 

 some parts of the loch. 



(5) Forfar Loch. 



Forfar Loch, which belongs to the Earl of Glamis, is situated a little 

 to the west of the town of Forfar. It extends in a S.W. and X.E. 

 direction, and is, according to the reduced Ordnance Survey map of 

 the district, a little over a mile in length by about three hundred and 

 eighty or ninety yards broad at the widest part. The land on the north 

 side and near the middle extends some distance out into the loch and 

 forms a kind of peninsula, and the loch is here much narrower than it is 

 to the east or the west of it. The elevation of the loch is about one 

 hundred and seventy-one feet above the level of the sea. The overflow 

 water finds an exit at the west end, and under the name of the " Dean 

 Burn " makes its way in a winding course of some ten or twelve miles to 

 the River Isla, which it joins a little to the north of the town of Meigle. 

 The east end of Forfar Loch has become so much filled up as to be little 

 better than a marsh ; a considerable portion of the shore is also fringed 

 with tall reeds. The loch for the most part is shallow, but there are one 

 or two places where the water is of moderate depth. Near the middle of 

 the loch I obtained a depth of twenty-one feet, while some distance to the 

 west of the peninsula already referred to, and comparatively near to the 

 north shore, a sounding of thirty-five and a-half feet — or almost six 

 faithoms — was obtained, and this was at a time when the loch was below 

 its normal level. Extensive beds of marl exist in certain parts of the 

 loch. A small quantity of this marl which was brought up in the tow- 

 net was found to consist to a large extent of dead molluscan shells, 

 Valvata piscinalis and Limncea peregra being specially numerous. 



Forfar Loch was examined on five different occasions — viz., in July 

 and November 1897, and in March, June, and September 1898. When 

 visited in July 1897 our lesearch was restricted to the shore, which was 



