THE WHEEL ANIMALCULES (ROTATORIA) 599 



63 (60) Lorica bearing long spines on dorsal surface. . Polychaetus Party. 

 Lorica turtle-shaped. Two species. 



Representative species (Fig. 905). . . . Polychaetus colUnsii Gosse. 



64 (s, 31) With or without lorica. Corona usually as broad as broadest 

 part of body and consisting of an outer wreath of cilia and 

 an inner interrupted wreath about the mouth, with sty- 

 ligerous processes between them. 



Suborder Hydatinina . . 65 



A heterogeneous group In external characters but showing evidence of close relationship 

 throughout. Corona never a perfect circle of two wreaths, with mouth in center. All loricate 

 forms without foot belong here. In all non-loricate forms foot present and ending in two toes, 

 side by side. In loricate forms foot when present ends in two toes, side by side, save in one 

 species, Gastropus slyH/er, where there is but one toe. The famiUes of this order are greatly 

 in need of a revision based on thorough comparative study of all the species. 



65 (73) Without lorica 66 



66 (70) Foot not sharply separated from body. 



Family Hydatinidae . . 67 



Large rotifers, body soft and segmented, of notommatoid characteristics, not greatly swollen 

 dorsally, nor compressed sidewise. Corona of typical form of suborder, or having a large 

 dorsal proboscis that bears two eyes. Foot lying in the body axis, not ventral; ending in two 

 short toes. 



67 (68, 69) No eye Bydatina Ehrenberg. 



Only one species (Fig. 906) Bydatina senla Ehrenberg. 



68 (67, 69) One eye Cyrtonia Rousselet. 



Only one species (Fig. 907) Cyrtonia tuba 'Ehx&nh&cg. 



69 (67, 68) Two eyes; corona with dorsal proboscis. . . . Rkinops Hudson. 



Only one species (Fig. 863, page 565). . Rhinops vitrea Hudson. 



70 (66) Foot decidedly set off from remainder of body. 



Family Notopsidae . . 71 



Body much swollen dorsally, flatter ventrally; cuticula slightly stiffer so that the body holds 

 its shape, or sometimes forming a weak but evident lorica. Foot forming a prolongation of 

 the ventral surface or extending ventrally; two small toes. 



71 (72) Two eyes Triphylus Hudson. 



Only one species (Fig. 908) Triphylus lacustris Ehrenberg. 



