History of the Hairy-bached Animalcules. 399 



these could be found, the other having vanished. Are they, 

 then, contractile vesicles ? The other viscera presented nothing 

 remarkable. 



Sp. 7. C. gracilis (Gosse). (PL i. Fig. 8.) This elegant 

 species, which I obtained from a pond near Leamington, in 

 July, 1850, is remarkable for the slenderness of its form, which 

 is not broader than that of G. larus, while it is about twice its 

 length. The head is dilated at the occiput, where it is abruptly 

 joined to the narrow neck, somewhat triangular, divided into 

 five well-marked rounded lobes, and fringed on each side with 

 laterally- diverging straight hairs. In the middle of the frontal 

 lobe is pierced the mouth, which is of the same form as in 

 0. SlacJcice, with slightly protrusile lips. The oesophagus is of 

 the ordinary form, but its anterior extremity is conterminous 

 with the front of the head, with no such structure, and no such 

 accessories as are seen in the species just named Its length 

 is unusual, for it extends nearly to the middle of the body, 

 where, just before it enters the intestine, the thick muscular 

 wail suddenly narrows, till it seems commensurate with the 

 tube itself. The intestine is concave at its commencement, or 

 rather, perhaps, it is furnished with a pancreatic gland on each 

 side, which, as is frequently the case in the Rotifera, is pointed 

 and ear-like. This suggestion, however, rests merely on the 

 form ; for I have not detected any bounding line between the 

 points and the intestine, nor was their substance clear, but 

 densely filled, as was that viscus, with finely granular matter. 

 The rounded termination, marking doubtless the position of 

 the cloaca, is on the descent of the back, some distance in front 

 of the foot-fork. 



I was not able to discern any internal organs besides the 

 alimentary canal, though the opacity caused by the hairs was 

 much less than usual. The anterior half of the body shows the 

 bases of the hairs, like very delicate dots set in quincunx. The 

 sides and back are armed with fine bristles curving backwards. 

 The points of the foot-fork are slender, sub-cylindrical, and 

 slightly dilated at the lips, which are decurved. 



The animal crawls impatiently about, apparently seeking 

 for food ; for I several times saw it eagerly snap at a Monad, 

 that roamed near, opening the mouth at the same moment. 

 Once I believe I saw it seize and swallow the prey, though as it 

 was the work of an instant, I could not be quite certain. I 

 have obtained but one specimen of this species. 



Genus III. — Dasydytes (Gosse). 



Head distinct : posterior extremely simple, truncate ; body 

 furnished with hair. 



