58 THE EOTIFEEA. 



traction. A non-ciliated cup-like head prolonged into an incurved di(jiliform appendage 

 (as a suhstitnte for the usual trochal disc), cnntrnctile and retractile." 



The Professor found eight specimens of this strange creature, each surrounded by a 

 group of Megalolrocha alhoflavicans, and all attached to the tubes of Plumatella diffusa, 

 in the Schuylkill river, U. S. It is considerably larger than M. alhoflavicans, and can 

 be readily distinguished with the naked eye, towering above the surrounding cluster of 

 Mcgalotrochce " like a giant in a crowd." It is a very diflicult animal to observe, as it 

 bends abruptly in different directions ; suddenly contracting and slowly elongatmg, and 

 scarcely ever for a moment remaining erect. It is translucent, whitish, with the thicker 

 portion of the body of a yellow or brown hue, due to the colour of the alimentary canal. 

 The corona is a cup prolonged on the dorsal side into an incurved lobe (PI. D, fig. 3). 

 It is capable of being expanded or contracted, protruded or retracted ; and when ex- 

 panded, tlic dorsal lobe is also extended, but remains somewhat incurved. There are 

 no cilia or setae on the edge of the cup or lobe, but both of them are bordered by a 

 delicate festooned membrane. When contracted, the lobe is rolled up spirally I PI. Y), 

 tig. 'db). A narrow, transversely wrinkled neck lies between the cup and the body. 

 Ko ciliary wreath has been noticed within the cup. There is generally no tube 

 present ; but in two instances the animal has been seen in a " copious colourless 

 gelatinous sheath." The cup converges into a pouch (the vestibule) occupying the 

 neck, which is seen to expand and contract from time to time. Longitudinal 

 muscles extend from the neck to the membrane surrounding the coronal cup, passing 

 along its walls. Ketractor muscles stretch from the body down the length of the foot. 

 The secreting, vascular, and nervous systems have not been observed ; neither have 

 any eyes or antennae in tlic adult female. The ovary is in the usual ventral position. 

 and the ova are large, and misogmented when extruded. 



Length, .', to ,', inch. Habitat, ychuylkill river, U. S. (Prof. Leidyj : rare. 



(ienus APSILUS, Mctsclniikoff. 

 GEN. Cil. Coronal cup wliolhj memhranous ; setae and foot absent. 



*Al'SILUS LENTIFOEMIS, MctSchuiJcoff. 



(PI. D, fig. 4.) 



Dicttjophora vorax (?) . . . Leicly, Proc. Acad. Nat. Sci. Pa. 1S57, p. 204, ami 



1S82, p. 218, pi. ii. fig. 7. 

 Ajisilus Icntiformis .... Mctschnikoff, Sicb. u. Kiill. Zcits. Bil. xvi. 18GC, p. 



34G, with figs. 

 Cupdopafjus bncincdax (?) . . Forbes, .4)h<;)-. iWon.Mo". J. 1882, pp. 102, 1.51, withfig. 



Apsilus vorax Foulke, Proc. ^ca(i.i\'«(. Sci. P<i. 1884, p. 37 pi. i. figs. 2, 5. 



Apsilus lentiformis .... Leidy, Proc. Acad. Nat. Sci. Pa. 1884, p. 50. 



Ilcrr E. Mctschnikoff found many specimens of this Kotiferon at Giessen in 18G6, on 

 the under side of the leaves of the yellow water-lily, to which they were attached by a 

 ehitinous ring on the ventral surface ; both in the young anil adult fenuile the foot was 

 absent. The coronal cup is wholly membranous, and destitute of either cilia or setae. 

 It is capable of having its edge all drawn close together into a point (PI. D, fig. 4a), and 

 of being wholly withdrawn within the body, so that it acts as a net, closing over any 

 prey that voluntarily enters it, and forcing it down into the chamber below it, which in 

 the Flosoilcs would be called the crop (fig. In, qj). At the bottom of the crop is a very 

 peculiar set of trophi (fig. 4c i. A broad stomach has a ciecal appendage on each side, and 

 a cloacal orifice on what appears to be the ventral side, but is really a portion of the 

 dorsal, having been drawn round by the animal's curving its body when attached to the 

 leaf. Tiierc arc two )« ar-shiipcd glands attached by their narrow ends to Uie crop. 

 There is a contractile vesicle opening into the cloaca, and from it, above, issues a 



