NO. 1382. 



THE AC A BIN A OR MITES—BAXKS. 



39 



Flli. 64.— PlOX.\ SP., .\XD P.\LPrs .\BOVE. 



The males have the body extended liehind, and there i.s a small median 

 petiolus. They live most commonlv in lakes and ponds, lu'endmvskia 

 and Steganaspls are each represented by one species. 



In Aturus the epimeral plate covers nearly the entire ventral sur- 

 face; o«e species is known from a small river in C^anada. Of Xi/sto- 

 /(off/.-i and Mideoj)sh but one species 

 is known in each; the latter is also a 

 common European water-mite. 



The species of Sperchon are often 

 found in cold and rapid mountain 

 streams. Three species are known 

 from Canada. They have the palpi 

 enlarged at base, and the second joint 

 bears a strong- spur below. The suck- 

 ing disks each side of the genital open- 

 ing are nearly concealed by lateral 

 Haps. The legs have no special swim- 

 ming hairs. 



> Limnesia is a large genus; three 

 species have been recorded from Can- 

 ada, two of them European. They 

 have a soft body; the hind legs are 

 well provided wnth swimming hairs, and the fourth tarsus lacks the 

 claws, l>ut is provided with a bristle at tip. The palpi have the l)asal 

 joints enlarged and often with a spur below. They usually occur in 

 lakes. 



Koenil'ea is represented by one species widely distributed in the 



northern parts of our country. The 

 species of llygrolxitts have soft bodies, 

 the slender legs destitute of true swim- 

 ming hairs, and the palpi have a spur 

 or tooth below. There are three 

 sucking disks each side of the genital 

 orifice. Four species are known from 

 Canada. 



Ata.e is one of the largest genera, 

 and Doctor AVolcott has worked out 

 some twelve species, and another has 

 since been added from Texas. The 

 genital opening is situate at the tip 

 of body, and the sucking disks each side are ten or more in number. 

 The legs have swimming hairs and the first pair is thicker than usual. 

 The palpi are enlarged at liase, and the fourth joint Ijears three papilla? 

 or spurs below. Most of the species occur, for at least a time, in certain 

 fresh-water mussels, particularly of the genera Unlo and Anodonta. 



Fig. G.5. — Lap.va of pion.\. 



