1884.] NATURAL SCIENCES OF PHILADELPHIA. 37 



ON A NEW SPECIES OF BOTIFER, OF THE GENUS AFSILUS. 

 BY SARA GWENDOLEN FOULKE. 



Among Spirogyra and Anacharis, gathered in Fairmount Park, 

 were noticed numbers of large rotifers, attached to filaments and 

 leaves of the plants. Though resembling in some respects the 

 forms, Dictyophora, of Leidy ; Apsilus^ of Meczinchow, and 

 Cupelopngus, of Forbes, this rotifer still possesses sufflcientl}^ 

 striking differences to warrant its being regarded as a distinct 

 species. The size of the specimens examined varied greatly, 

 the maximum size being one-fiftieth of an inch, from the top of 

 the extended net to the end of the body. 



The ventral outline of the body is ovoid ; the lateral outline is 

 crescent-shaped ; while the dorsal outline is similar to the ventral. 

 Instead of rotatory organs, this rotifer possesses a membraneous 

 cup or net, near the base of which, on the ventral side, are two 

 lateral antennae, as in Apsiliis lentiformis. 



When the net is retracted, the antennae are also withdrawn into 

 the body, and concealed from view. This is an unusual habit 

 among the Rotatoria, the antennae being usually situated upon 

 the body, and remaining exposed so as to act as sentinels 

 when the rotatory organs are retracted. This net is used for 

 the capture of food, consisting of the larger infusoria closino- 

 over an}' organism which is attracted into it. After capture, the 

 food passes through the oral aperture into a large, sac-like 

 passage-way, and thence into a second pouch, which extends across 

 the bod}' in the form of a much-wrinkled bag. The two ends of 

 this bag widen into sacculated pouches, which are used as store- 

 houses for the food while softening. This organ may be reo-arded 

 as the stomach proper, being filled with a greenish granular fluid 

 which performs the office of a true gastric juice, softenino- the 

 tissues of the contained food, in preparation for the action of the 

 mastax. When this maceration has been sufficiently prolonged, 

 the food is forced, by muscular contraction, out of its recess, 

 along the narrow central portion, past the mastax and into the 

 opposite pouch. As the stream of food passes, the mastax, 

 which is situated centrally at the bottom of the stomach, turns, 

 so as to face the stream of mingled food and gastric fluid ; and 

 works actively, chopping and bruising such portions as come 



