340 



C. T. HUDSON. 



depend on the absence or presence of eyes, and on their 

 number; and here Ehrenburg is not right as to his facts. 



For striking out from his fifteen genera of the Mono t roc ha, 

 the three already mentioned with Cyphonautes, ten of the 

 remaining eleven genera have two eyes when young. 



Though the use of the red eye-spots has on this occasion 



Fig. 6. 



EuManis triquetra 



Pterodina patina. 



Fig, 5. — a. Principal cilary wreath. c. Antenna. d. Cephalic ganglion. 



/. Mastax. h. Gastric gland. _;. Stomach, k. Intestine. /. Anus. 



n. Contractile vesicle, o. Ovary, r. Foot. 

 Fig. 6. — a. Principal ciliary wreath, b. Secondary ditto, e. Eyes. ,/. Mastax. 



h. Gastric gland, e. Salivary glands, j. Stomach, o. Ovary, q. Muscle. 



r. Foot. 



been unfortunate, still I cannot agree with those who object to 

 their being used as generic characteristics, and who doubt of 

 their being eyes at all. In some of the Kotifers, as in 

 Triarthra longiseta (fig. 8), Pedalion mirum (fig. 12), 

 and Conochilus volvox, they are beautiful little diaphanous 

 spheres, resting on plates of ruby pigment, while the splendid eye 



