Tht Rotatorian Genus Diaschiza. 133 



■exceedingly rare and uncommon rotifers : e.g. we were the first to 

 record Ploesoma Hudsoni, south of Scotland ; and have added a 

 new species rostrata (nobis) to the genus Diglena. 



Hence also we have gained an intimate knowledge of this 

 genus, having obtained there every species of Diaschiza mentioned 

 in this monograph (except D. tenuiseta) and having added two new 

 species to the genus, viz. " ventripes " and " Derbyi." 



Diaschiza exigua Gosse. 

 PI. III. figs. 10 and 10a. 



BIBLIOGRAPHY. 



Hudson & GoasB.— The Kotifera. London, 1889, vol. ii. p. 78, pi. 22, fig. 13. 



Spec. Cliar. — Body very small, wedge-shaped ; head rather 

 narrow from a dorsal view ; neck well marked, specially deeply 

 constricted on dorsum ; face sub-prone ; lorica flexible ; dorsal 

 -cleft large, deep, more decided than usual ; lateral cleft wide, deep, 

 more decided than usual ; eye cervical, large, double ; foot small ; 

 toes about A length of rest of body, furcate, blade-shaped, slightly 

 decurved. 



In April 1901, we found great quantities of this minute 

 Diaschiza in the large lake in Knowsley Park, Lancashire, and 

 were able to make very careful observations. 



Gosse's description is good ; but the dorsal cleft is well marked 

 and deep. 



Viewed dorsally, the body tapers rapidly from the broad 

 middle to almost a point above the very small foot. This gives it 

 a wedge-shaped appearance, which may be taken as the most 

 distinctive feature of the species. 



There is a trace of a fleshy projection over the foot, as in 

 D. sterea, but less conspicuous. 



The eye, which is cervical, consists of two large hemispherical 

 spots welded together inside the lower end of the brain-sac. 



The setae on the foot are well marked. 



The toes taper evenly throughout, and are slightly decurved. 



The jaws have the incus of moderate length, thick, and 

 terminating in a small recurved bulb or fulcrum. The manubria 

 are plain thin rods, not crutched. 



Its food is flocculent matter. 



Size. — Total length ^ ^ in. (98 fi) ; toes alone yoVo * n - (23 h) ', 

 breadth ¥ ^ in. (32 fi) ; height ¥ ^ in. (32 fi). 



Common, but local. 



