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Vol. VII. DETROIT, FEBRUARY, 1887. No. 2. 



ORIGINAL COMMUNICATIONS, 



OBSERVATIONS ON CH^TONOTUS. 



[Concluded.] 

 DR. ALFRED C. STOKES, TRENTON, N. J. 



1. Chcetonotus [Icthydium) podura, Ehr. 

 ^"T^HE body, according to Ehrenberg, is linear oblong, the 

 -*• anterior extremity swollen, sometimes three-lobed, often 

 slightly constricted, and the posterior end forked. He gives 

 the length as varying from j^g to y^ inch. The few indi- 

 viduals observed by me have the entire cuticular surface smooth 

 and naked, with the exception of the four dorsal hairs already 

 referred to as present in every species, and the two longi- 

 tudinal bands of ventral cilia. The oral annulus is not beaded. The 

 egg — only one specimen of which I have seen, and this I neglected 

 to measure — was entirely smooth. The individuals in the waters 

 near my home are rather smaller than the largest measurement 

 given by Ehrenberg. 



2. Chcetonotus sulcatus, sp. nov. — Plate I, tig. 15. 

 The peculiarity of this form is in the deep, transverse 

 sulcatioiLS or furrows, usually conspicuously developed on the 

 back and sides. Rarely they are almost obliterated, or repre- 

 sented by a few low ridges crossing the back transversely. The body 

 is very soft and flexible, and more nearly hyaline than that of any 

 other thus far observed, and the lateral margins, which are often so 

 flattened as to give the body a winged appearance, are beautifully 

 crenated, as is the back also when seen in profile. The posterior 



