668 Transactions of the Society. 



Callidina pinniger sp. n.. plate XV. figs. 5 to 7. 



Specific Characters. — Size moderate. Trunk with many pro- 

 cesses, those on anterior trunk-segments broadly expanded, fin-like ; 

 posterior trunk processes, stout flattened spines, with bulbose 

 bases. Some smaller dorsal processes on foot, variable, scale-like, 

 or spoon-shaped. Dental formula, 2 -f- 1/1 4- 2. 



The general form is like C. mvltispinosa. The spurs are small. 

 There are two ventral necklets of papillae on the head. The dorso- 

 lateral processes (on each side of the antenna) of the first cervical 

 segment are low and two-lobed. 



There are three of the expanded lateral processes on each side, 

 on distinct segments. They are usually expanded upwards, wedge- 

 shaped, and look like fins or flippers. 



Lie transverse rows of dorsal spicules, characteristic of G. multi- 

 spinosa, are usually absent, but an example has been seen which 

 had one spicule of the anterior row, close to the third flipper, and 

 another had four spicules of the posterior row. 



The stout posterior trunk-spines are usually five on each side. 

 They are strongly compressed, acute, and the greatly swollen bases 

 appear to articulate with the skin. Those of the first row are 

 largest — one is quite lateral and the other is on the next dorsal 

 skinfold ; the second row is similar, but smaller ; the last spines 

 are single and sublateral. 



The foot is kept so contracted that the true position of the small 

 processes, whether on anal segment or foot, cannot be seen. They 

 are variable, and are either, as in plate XV. fig. 5, scale-like and 

 overlapping, or narrower, spoon-shaped, and standing apart. They 

 are from six to eight in number. 



There may be other small foot-spines hidden by the contraction 

 of the foot. 



Though a large number of skins were seen, there were very few 

 living examples, and it was only once seen to feed. The head in 

 the feeding attitude did not differ perceptibly from that of C. 

 multispinosa. 



Length, when feeding, about 200 p,, to 250 p, when creeping. 



The flipper-like processes are in no degree functional as fins or 

 swimming organs, so far as my observations of the few living 

 examples show. Like the spines of C. multispinosa, they seem to 

 change position merely with the varying tension of the skin, and to 

 be purely defensive weapons. 



Rotifer longirostris Janson (J8). — -Type, frequent, form with 

 thick plates on the trunk, like those of Pliilodina tuberculata Gosse. 



Var. finibriaia Murray (5). — Several examples. 



Var. bitorquata var. n. (plate XV. fig. 8). — Besides the festoon 

 of conical processes close below the mouth, as found in the type, 

 there is a similar row of larger leaf-like processes on a lower neck- 



