SCOTTISH TARDIGRADA, COLLECTED BY THE LAKE SURVEY. 643 



M. islandicus, Richters. Ness? (record untrust- M. sattleri, Richters. Earn. 



worthy). M. papillifer, Murray. Morar, Ness. 



.1/. dispar, Murray. Tay. M. macronyx, Duj.? (All records doubtful.) 



M. ambiguus, Murray, Ness (egg). M. annulatus, Murray. Morar. 



M. ptdlari, Murray. Gryfe, Ness. Diphascon chilenense, Plate. Ness. 



M. hastatus, Murray. Tay (egg). D. spitzbergen-se, Richters. Ness. 



M. oberhauseri, Doy. Ness (other records doubt- D. angustatum, Murray. Ness. 



ful). D. scoticum, Murray. Morar. 



M- ornatus, Richters. Ness (other records doubt- D. bullatum, Murray. Leven (Evans). 



ful). D. oeulatum, Murray. Ness. 

 M. tuberculatum, Plate. Morar. 



Tardigrada of Orkney and Shetland. 



The Tardigrada of these remotest northern fragments of Britain were studied during 

 September 1906, while the lochs of these islands were being surveyed. 



A large number of collections were made, at the margins of lakes, in ponds, and 

 among moss, from every kind of situation and at all elevations, from sea-level to the 

 tops of the highest hills. 



When those collections were examined during the succeeding months, it soon 

 became apparent that they were of the highest interest. 



The first general fact of interest was that there were a number of species previously 

 only known in more northern lands, some of them only within the arctic circle. E. 

 islandicus, M. coronifer, M. crenulatus, M. harmsworthi are such species. All of 

 these, except E. islandicus, were unknown outside the arctic circle till they appeared in 

 Orkney or Shetland. 



Another interesting fact was the occurrence of a number of peculiar species 

 previously unknown. Such were M. zetlandicus and M. orcadensis. Several other 

 species, discovered about the same time in Scotland, were shown, by simultaneous 

 studies of Mr Bruce's collections, to extend into the extreme north. 



A curious fact is the abundance of species of the genus Macrobiotus, and the 

 extreme scarcity of Echiniscus. Thirteen species of Macrobiotus were found, and only 

 six of Echiniscus. The discrepancy is greater than appears from these figures, as all 

 but 3 or 4 of the species of Macrobiotus were frequent and abundant, while of the 

 Echinisci only E. arctomys was at all frequent, E. mutabilis was found several times, 

 E. gladiator var. exarmatus several times, but only in one locality, and all the others 

 were known from single examples. 



The group of species to which belong M. coronifer, M. crenulatus, and M. 

 harmsworthi is only known to occur in northern lands ; indeed, till the finding of these 

 three species in Shetland, no member of the group was known outside the arctic circle, 

 within which they have a wide distribution. This group is characterised by a crescent- 

 shaped ridge in front of each pair of claws, the ridge often spiny or wrinkled. 



Comparing the two groups of islands, as may be done by referring to the accompany- 



