330 DESCRIPTION OF [Rotatoria. 



FAMILY XXIII.-ICHTHYDINA 



Contains all those rotatory animalcules which possess a 

 single continuous rotatory organ, not cut or lobed at the 

 margin. They are destitute of lorica or shell. In Ptygura 

 and Glenophora their wheel-like organ is in the form of a 

 circle, and serves for the purposes of locomotion ; in the 

 other genera it is band-like, long, elliptical, and upon the 

 ventral surface. A forked foot-like process is met with in 

 Chaetonotus and Ichthydium, and a simple one in the 

 others. A simple conical alimentary canal, with a long 

 thin oesophagus, without teeth (?), is seen in Ichthydium and 

 Chaetonotus; Glenophora has a short oesophagal portion, 

 and two single teeth, and Ptygura an elongated stomach 

 and three teeth. Pancreatic glands are seen only in Chae- 

 tonotus and Ptygura; neither coecum nor gall-ducts are 

 visible in any of the genera. The male reproductive 

 organs have not been observed in any form, and the female 

 ones consist, in two genera, of a large ovarium, with a few 

 large ova. The two red frontal eyes, seen in Glenophora, 

 are indications of the existence of a nervous system, and 

 the bristly hairiness of the back of Chaetonotus is worthy 

 of remembrance. 



This family comprises the following genera: 



[f with a simple truncated tail-like 1 . 

 J foot (Pseudopodium) / Pt yg ura " 

 hair absent \ 

 I with a forked tail-like foot Ichthydium. 

 hair (bristle-like) present Chaetonotus. 



Eyes present (two frontal) Glenophora. 



Genus CXXXIV. PTYGURA. The wrinkled-tail Ani- 

 malcules are destitute of eyes and hair, but have a simple, 



