Notes, Reviews and Comments. 187 



Mr. Tyrrell, whose researches in hydrachnidae, sarcoptidre, etc., are 

 well known to the members of our Club, has kindly prepared the following 

 notice of Dr. Koenike's paper on " Nordamerikanische Hydrachniden" 

 for the Naturalist. 



II. North American Water-Mites. 



This report of sixty octavo pages contains a clear and exhaustive 

 description of a collection of Canadian Water-mites, made by Mr. 

 Tyrrell, of the Geological Survey Department, in this city, partly in the 

 vicinity of Ottawa, and partly in the lakes and streams of the Rocky 

 Mountains, between the Canadian Pacific Railway and the Inter- 

 national Boundary line. 



Dr. Koenike here describes thirty species, belonging to fourteen 

 different genera, sixteen species and one genus being new. The 

 descriptions are illustrated by seventy-two beautiful figures, arranged 

 on two folding and one single plate. The paper will be a classic in the 

 literature of these minute and usually bright coloured inhabitants of 

 clear water, as it contains the first full and systematic description of a 

 collection of Water-mites from North America. 



The species of more particular interest to the Naturalists of Ottawa 

 are Eylais extendens. the small red mite so often seen swimming among 

 the weeds in quiet water. Mideopsis orbicularis, with its clear yellow 

 body, and light red band down the back, was found in Patterson's 

 Brook, near Bank street, on the 20th of January, 1883. Tytrellia 

 ci/citlaris, a reddish-brown water-mite, -^ inch in length, with oval 

 or almost circular dorsal outline, found crawling on the mud in 

 a pond at Deschenes, on one of the Field Club Excursions on 

 the 2nd of September, 1882. This species is the type of the new- 

 genus Tyrrellia. Limnesia anomala, a rather large mite, with sky blue 

 legs found in Meach's Lake. Atax ypsilophorus parasitic in the gills 

 of Anodonta fragilis. Atax tngens, a milk-white form, as large as a 

 pea, found parasitic in the gills of Anodonta fragilis and Unio com- 

 planatus from Meach's Lake. Atax fossulatus parasitic in the gills of 

 Unio luteolus from the Rideau river. 



Most of the specimens supplied were collected in Alcohol, but 

 water-mites, soft-bodied and generally brightly coloured creatures, are 

 said to be best preserved in a three per cent, solution of Chloral Hydrate. 



