642 MR JAMES MURRAY ON 



M. macronyx and M. dispar appear to be almost confined to ponds and lakes. 



Of the 41 species of Tardigrada recorded for Scotland, 31 have been found in the 

 lochs : the remaining 10 are as yet only known as moss- dwellers. 



The subject is in this paper treated under the various headings — " Tardigrada of 

 the Scottish Lochs " ; " Tardigrada of Orkney and Shetland " ; " Scottish Alpine 

 Tardigrada " ; and " Notes on the Genera and Species." 



The Tardigrada of the Scottish Lochs. 



In the previous paper on the Tardigrada of the Scottish lochs there were enumerated 

 21 species. Despite this considerable number of species, it must not be supposed that 

 very many Tardigrada are normal inhabitants of permanent waters. The Tardigrada 

 were obtained among mosses and other plants growing round the margins of the lochs ; 

 and though rightly included in the lake fauna, many of them were doubtless only 

 casually present. The Tardigrada are most at home among mosses which are inter- 

 mittently moist. Some species of Macrobiotus are of usual occurrence in ponds, peat 

 bogs, and other permanently moist places. M. macronyx has been usually regarded as 

 the only really aquatic species. Some similar species, which are described in this 

 paper, seem also to be peculiar to ponds. The genus Echiniscus rarely occurs in ponds 

 or lakes. 



Since the previous paper appeared, ten additional species have been found at lake 

 margins, making the total of 31 species for the Scottish lochs. 



In the appended list of the 3 1 species it was necessary to include one or two which, 

 there is reason to believe, were wrongly identified, as they had been recorded in the 

 previous paper. Those doubtful or erroneous records are indicated in the list. M. 

 macronyx and M. islandicus are not yet certainly known to occur in Britain. 



There is a certain doubt whether E. gramdatus, E. quadrispinosus, and M. tuber- 

 culatus are identical with the species described under those names, but they are 

 certainly very close to them. 



Though it is certain that 29 indubitably distinct species have been found in our 

 lochs, a few of the determinations are open to doubt. The following table gives the 

 distribution in the lochs so far as known. 



List of Species in Scottish Lochs. 



I'lrldniscus ardomys, Ehr. Morar, Ness, and Earn. E. spitsbergensis, Scourfield. Morar, Earn. 



E. mutabilis, Murray. Morar, Ness, Earn, Tay. E. quadrispinosus, Richters. Morar, Ness. 



E. gladiator, Murray. Morar, Ness. Milnesium tardigradum, Doy. Ness. 



E. wendti, Richters Morar, Elarn, Tay. Macrobiotus hufelandi, C. Sch. Lomond, Earn, 



A', rdiculatus, Murray. Morar, Ness, Earn, Tay. Gelly, etc. 



E. oihormse, Richters. Ness, Earn. M. intermedius, Plate. Morar. 



E. granulatus, Doy. Morar, Ness, Tay. M. echinogenitus, Richters. Morar, Ness. 



