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XII. — Scottish National Antarctic Expedition : Tardigrada of the South Orkneys. 

 By James Murray. Communicated by W. S. Bruce. (With Four Plates.)* 



(MS. received May 11, 1906. Read May 28, 1906. Issued separately August 31, 1906.) 



Introduction. 



While engaged in investigating the Tardigrada of the Scottish Lochs, I was desirous 

 of comparing our Tardigrade Fauna with that of other parts of the world, and it 

 occurred to me that the then recently returned Scottish Antarctic Expedition might 

 furnish some suitable material. On applying to Mr R. N. Rudmose Brown, in the 

 absence of Mr Bruce, I was courteously supplied with various samples of moss which 

 I judged likely to contain Tardigrada. 



On examining this moss it was found that Tardigrada were indeed numerous in it, 

 and although not in very great variety, some of the forms were of considerable interest. 



The moss bad not been collected with a view to the study of its microfauna, but 

 solely as botanical specimens, and was therefore impregnated with some preservative 

 which had killed all the adult animals and most of the eggs. This is unfortunate from 

 the point of view of the present investigation, as I should otherwise have been able to 

 hatch out the Tardigrada and other animals and study their development. A much 

 more complete account of the Tardigrada could in that case have been given. 



Besides Water-Bears and their eggs, there were numbers of Bdelloid Rotifers and 

 eggs, Nematodes of at least two species, Rhizopods, and, lastly, very many Mites of at 

 least four species. 



The eggs of the Mites seemed to be most impervious to the preservative, and many 

 hatched out, but were very quickly killed by the trace of the naphthaline in the water. 

 The only other animals seen alive were one Bdelloid of the genus Rotifer, and a 

 Nematode, which moved feebly for a short time after moistening. 



The adult Tardigrada were in very poor condition, most having been long dead, and 

 the flesh all reduced to a formless paste. In this condition, when the specimens were 

 subjected to pressure, all the details of internal structure were lost, and the most useful 

 method of discriminating species rendered of no avail. Even the tough, hard parts of 

 the teeth and pharynx were partially wasted away. The basal portions of the teeth 

 had in most cases merged in the general paste, though the distal parts were intact. 

 The detail had therefore to be studied under moderately low powers, and without 

 exercising much pressure. 



A few examples were in that state of rigor so characteristic of Water-Bears, in which 

 the internal parts are in good order, and may be better studied than in active animals, 



TRANS. ROY. SOC. EDIN., VOL. XLV. PART II. (NO. 12). 45 



