Phihdinaea.'] infusorial animalcules. (>65 



Dujaj'din figures a species of Callidina, which he would namo 

 Callidina constricta, on account of the contracted form of its rotary 

 apparatus. Its jaws present a row of closely set parallel teeth. 

 Length l-52nd. 



Callidina Helens (Gosse.) — Body spindle-shaped, jaws furnished 

 vdih. two distinct teeth. Length l-45th. Perhaps this is no other than 

 Professor Ehrenberg's C. elegans, of which he describes the jaws as 

 having many delicate teeth. I have, however, examined numerous 

 specimens, and have always found them distinctly two-toothed. 



Genus Hydrias. The Water-turner is Afiican. It is devoid of 

 eyes, proboscis, and the Kttle horn-like processes at the foot ; the two 

 small rotatory organs, or wheels, are supported on pedicles or arms. 



An cesoj^hageal head, and an ovarium, with a large ovum, have 

 been seen by Ehrenberg. The fonn is like a naked Pterodina. 



H. cornigera. — Body ovate, hyaline ; foot attenuated, resembling a 

 furcate tail. Fig. 474 represents an animalcule extended. Pound 

 with OyciUatoria, in standing water, from a small spring by Siva, in 

 the Oasis of Jupiter Ammon. Length 1-1 90th. 



Genus TypHLiNA. The hlind Vibrator, like the last, is African. 

 Devoid of eyes, proboscis, and horn- like processes at the base of the 

 foot ; but its little wheels are sessile. It resembles a very small 

 Rotifer y without frontal proboscis or eyes. 



T. viridis. — Body oblongo-conical, small : it is represented in 

 group 475. Found by Drs. Hemprich and Ehrenberg in a pool near 

 Cairo in Egyj^t, in such numbers as to colour the water green. 

 Length l-720th. 



Genus Eotifee. The prohoscised Rotatoria. — Eyes two, placed 

 upon the frontal proboscis ; foot provided with little horn-like pro- 

 cesses, and the two toes bisulcate at their apices. A double rotatory 

 organ (considered by Cuvier, and others, as a respiratory apparatus), 

 furnished with muscles, is seen in all the species ; also longitudinal 

 and foot muscles in three of them ; a furcate foot and horn-like pro- 

 cesses in four species ; in R. citrinm, the pincer-like portions of the 

 foot appear to be tri-pointed ; in B. erythraeus, they were seen to be 

 drawn in. In four species a muscular oesophageal head, with jaws, 

 each two-toothed, is seen ; in three species the alimentary canal is 

 filiform, with a vesicular expansion at the extremity ; it has no 



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