109 



Genus CALLIDINA, Ehrenberg. 



GEN. CH. Eyes absent. 



Although this genus differs technically in so slight a degree from those which we 

 have considered, yet it can be generally recognized by its slender, pointed shape, its 

 smaller size, and the abundant corrugations of its skin. Its internal organization, with 

 the exception of the eyes, is 6 precisely that of Rotifer, that it requires no special descrip- 

 tion. One of the species (Mr. Gosse's G. bihamata] possesses a very obvious pair of 

 those dorsal hooks which are so characteristic of the nearly related Melicertadce, and 

 which are to be found also in the still humbler and more closely connected genus 

 Adineta. 



C. ELEGANS, Ehrenberg. 



Callidina elegans .... Ehrenberg, Die Infus. 1838, p. 482, Taf. Ix. fig. 1. 

 . . . . Perty, Zur Kenntniss kleinst. Lebensf. 1852, p. 43. 



Pritchard, Infusoria, 1861, p. 702, pi. xxxiv. figs. 470-3. 



[SP. CH. Body fusiform, abruptly enlarged centrally, strongly fluted, collared; 

 frontal column thick, truncate, ciliate, with a decurved proboscis ; jaws with no promi- 

 nent teeth ; foot thick ; spurs moderate. 



This species, the only one of the genus known to Ehrenberg, I find not uncommon 

 in various waters : but it is only by careful observation that it can be distinguished from 

 its congeners. The corona is scarcely wider than the body, the double disk being very 

 little more than a full circle, or two circles very slightly separated, when seen quite 

 vertically. The column is short, unusually thick, with a minute acute proboscis over- 

 arching the dorsal edge of its tip. The antenna longer than width of corona, slender, 

 subequal throughout, flexible, truncate, carrying (apparently) a short terminal brush of 

 fine setae. A swelling collar above the antenna. The trunk, bounded above and below 

 by a strong transverse fold, is abruptly swollen, impressed with strong longitudinal 

 plaits, frequently visible as the animal turns. The foot is thick ; the penultimate spurs 

 middling ; the three toes well developed. The outline is very variable. The trunk is 

 tinged with clear yellow-umber, which is abruptly defined at both ends ; the extremities 

 being colourless, and very hyaline when stretched in extension. 



The trophi, when viewed quite dorsally, have much of the form seen in the Rhizota, 

 as figured (for Limnias) in my mem. " On Hand. Org." fig. 71 : the rami being long 

 and pointed, and having a projecting handle-like knob. After keen scrutiny, I cannot 

 discover any teeth crossing them, or anything to break the uniformity. I hence con- 

 clude that there are only the very close minute lineations, which Ehrenberg describes. 

 A vanishing shadow of a curved line on each side may represent the mallei, but quite 

 undefined. The restlessness of the animal precludes fine definition. It is most im- 

 patient, incessantly moving, not still for an instant. It rarely swims, but perpetually 

 crawls by alternate elongation and shortening, in a course excessively devious. 



Length, T ^ to -^ inch. Habitat. Button Park Ditch ; Woolston Pond : rather 

 common (P.H.G.). P.H.G.]. 



C. BIDENS, Gosse. 

 (PI. X. fig. 8.) 



Callidina bidens .... Gosse, Ann. Nat. Hist. 2 Ser. vol. viii. 1851, p. 202. 



[SP. CH. Surface closely corrugated ; spurs minute, conical, pointed ; teeth two. 



I obtained this species at Messrs. Smith and Beck's in 1849, from a nearly putre- 

 scent infusion of hay, in which it was swarming almost to the exclusion of everything 

 else. Its manners differ much from those of other Philodinada. It is, if I may use 



