1884.] NATURAL SCIENCES OF PHILADELPHIA. 39 



of purplish brown bodies, varying in intensity of tint, whose 

 character is as yet unknown. 



The rotifer, in the adult state, is tailless, eyeless, and attached 

 in a semi-recumbent position, from which it is incapable of 

 detaching itself, and without the power of re-attaching itself 

 when displaced. 



In the young state it has two red eye-spots ; a clums}' telescopic 

 tail, terminating in a broad, cup-shaped sucker ; and is so actively 

 free swimming that no accurate drawing could be obtained. In 

 this undeveloped state the rudimentary^ net is a thick fleshy 

 triangle, the truncated apex of which is inserted into the body, 

 while the base is surrounded by a wreath of cilia, on the closed 

 space within which the eye-spots are set. There is in this stage 

 no opening to admit nourishment. 



The development of this form into that of the very dissimilar 

 adult state is most interesting, and well worth the time and 

 patience necessaiy to observe it. 



It is proposed to unite the three forms, Dictyophora voracc, 

 Apsilus lentiformis, Gupelopagus bucinedax, and the form 

 described above, in one genus under the name Apsilus. The name 

 Dictyophora would have the first claim for adoption, but it is 

 already in use in two other branches of science, so that the choice 

 must fall upon the next in order of priorit3\ The specific names 

 given to the forms by their discoverers are retained. The history 

 of the genus is as follows: In 1857, Dr. Jos. Leidy discovered 

 and described a form which he named Dictyophora vorax. In 

 1866, Meczinchow described and named a similar form which he 

 named Apsilus lentiformis, the diflferenees from Dictyophora 

 being as follows : shape of the cup ; presence of two lateral 

 antennas ; and presence of a conspicuous ganglion of the pouch. 



In 1882, S. A. Forbes described a form which he named Gupel- 

 opagus bucinedax, designating it as a new genus. The differences 

 between this and the two forms previously described are as 

 follows: Gupelopagus differs from Dictyophora in the shape 

 of the net, and in the general shape of the body, the difference 

 in these particulars being very marked. It differs from Apsilus 

 in the absence of the ganglion of the pouch, in the absence of the 

 lateral antennae, and in other minor particulars. 

 • The species described by the author varies from the foregoing 

 in the following respects: it differs from Dictyophora in the 



