37 2 The Upper Elf Loch, Braids. [Sess. 



towards more exact knowledge has been made in recent years, 

 though much yet remains to be done in this interesting field 

 of study; and the worker in it will usually find abundant 

 material in the Upper Elf Loch. 



The Desmids have been increased during the past year by 

 some additional forms, bringing up the list to eight genera and 

 fifteen species. Three fresh species of Closterium were found, 

 two of Cosmarium, and one each of Arthrodesmus, Pediastrum, 

 and Ankistrodesmus, the last often now included amongst the 

 Palmellacese. A few Diatoms have also been observed, includ- 

 ing two species of Stauroneis and two of Navicula, with one 

 species each of Pinnularia, Gomphonema, and Cymbella. The 

 semi-stagnant condition of the water in this tarn no doubt 

 accounts for such a paucity of Diatoms. 



Coming to the unicellular Infusoria of the Animal Kingdom, 

 we are met at the threshold by a similar state of matters to 

 that which still prevails amongst the single-celled plants, 

 seeing that " many of the reputed Infusoria may be but larval 

 forms of higher organisms, instead of being themselves com- 

 plete animals." 1 This group also furnishes a most interesting 

 study for the microscopist, with its varied and beautiful forms, 

 and its numerous problems still awaiting solution. No fewer 

 than sixty-two species of Infusoria from this little hill-tarn 

 have now been identified for us by Mr John Hood of Dundee, 

 and forty-four of these have been added during the past year. 

 Amongst the latter are three species belonging to a class not 

 represented in our former paper — viz., the Tentaculifera or 

 Suctoria. One of these, the " hairy - backed animalcule " 

 (Chcetonotus larus), is here included in this class, though some 

 writers relegate it to the Turbellaria, and others to the 

 Rotatoria, of which they regard it as an aberrant form. A 

 very good description of Chaetonotus, with figures, is given 

 in the well - known ' Marvels of Pond - Life,' by Henry 

 J. Slack, F.G.S. 



While the Upper Elf Loch is thus abundantly supplied with 

 representatives of the Infusoria, the members of the Eotifera 

 present in it are yet more numerous. During the past year the 

 following accessions have been made to their number. In the 1st 

 order, the Rhizota, four additional species have been observed, — 



1 Carpenter's 'The Microscope and its Revelations,' 7th ed., p. 679. 





