50 proceedings op the academy op [1884. 



March 4. 

 The President, Dr. Leidy, in the chair. 

 Thirty-seven persons present. 



A paper entitled " The Rufous or Thatching Ant of Dakota 

 and Colorado," by Henry C. McCook, D. D., was presented for 

 publication. 



Dictyophora as Apsilus vorax. — Prof. Leidy stated that Mr. 

 Uselma C. Smith, last week, had afforded him the opportunity of 

 examining a wheelless rotifer, attributed to ^psiZws, which he had 

 found abundantly, last autumn, in a pond at Fairmount Park, 

 attached to ^nac/? art's, and likewise in the Schuylkill River, near 

 by, on Potamogeton. A number of specimens were observed 

 attached to the sides of the jar, as well as to both the plants con- 

 tained tlierein. The specimens being more readily detached from 

 the latter than from the glass vessel, they were seen under more 

 favorable circumstances than previously. They were recognized 

 as Dictyophora^ first described in 1857 ; and as a result of the last 

 examinations, Prof. Leidy was led to the opinion that this, the 

 Apsilus lentiformis Meczinchow, the Cupelopagus hucinedax 

 Forbes, and the Apsilus bipera, recently communicated to the 

 Academy by Miss Foulke, all pertain to the same species. In the 

 recent specimens he had recognized the lateral antenna3 ending in 

 exceedingly delicate and motionless cils, as indicated by Meczin- 

 chow, and which previously, from the wrinkled condition of the 

 specimens detached from hard objects, had escaped his attention. 

 The structure described by Meczinchow as a ganglion, he could 

 not satisfactorily distinguish as such ; nor had he been able to 

 detect the arrangement of the excretory canals, as represented 

 by the same author. The lateral view of the animal accords with 

 the figure of Cupelopagus as given by, Forbes; the body being 

 ovoid, with the mouth of the prehensile cup oblique, and appearing 

 more or less unequally two-lipped. In this view the antenna? are 

 undistinguishable. In all the forms described, the prehensile cup, 

 in the same manner, is projected from and withdrawn within the 

 mouth of a compressed oval or nearly spherical carapace, dotted 

 with minute tubercles. The prehensile cnp, substituting the 

 usual rotary organs of rotifers, communicates with a capacious, 

 variably sacculated and dilatable stomach, followed by the ordi- 

 nary gizzard with its mastax,and then a second sacculated stomach. 

 The ovoidal cloacal pouch opens by an aperture, with radiated 

 folds, externally, some distance in advance of the fundus of the 

 carapace. 



The size of the different specimens described varies greatly, 



