58 THE EOTIFEEA. 



traction. A non-ciliated cup-like head prolonged into an incurved dig itiform appendage 

 (as a substitute for the usual trochal disc), contractile and retractile." 



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

 group of Megalotrocha alboflavicans , and all attached to the tubes of Plumatelladiffusa, 

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

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

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

 bends abruptly in different directions ; suddenly contracting and slowly elongating, 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 (PL D, fig. 3). 

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

 panded, the 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 (PI. D, 

 fig. Qb). A narrow, transversely wrinkled neck lies between the cup and the body. 

 No 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. Retractor 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 the adult female. The ovary is in the usual ventral position, 

 and the ova are large, and unsegmented when extruded. 



Length, .,\ to ^V inch. Habitat. Schuylkill river, U. S. (Prof. Leidy) : rare. 



Genus APSILUS, Metschnikoff. 

 GEN. CH. Coronal cup wholly membranous ; setae and foot absent. 



*ArJLUS LENTIFOKMIS, Nctschnikoff. 

 (PI. D, fig. 4.) 



Dictyophora vorax (?) Leidy, Proc. Acad. Nat. Sci. Pa. 1857, p. 204, and 



1882, p. 248, pi. ii. fig. 7. 

 Apailus Icntiformis .... Metschnikof'f, Sicb. u. Koll. Zcits. Bd. xvi. 1866, p. 



346, with figs. 

 Cupelopagns bucincdax (?) . . Forbes, Amcr. Mon. Micr. J. 1882, pp. 102, 151, with fig. 



Apsilus vorax Foulke, Proc. Acad. Nat. Sci. Pa. 1884, p. 37 pi. i. figs. 2, 5. 



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



Herr E.Metschnikoff found many specimens of this Rotiferon at Giessen in 1866, on 

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

 chitinous ring on the ventral surface ; both in the young and adult female 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 Floscules would be called the crop (fig. 4.a, cp}. At the bottom of the crop is a very 

 peculiar set of trophi (fig. 4c). A broad stomach has a coecal 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. There are two pear-shaped glands attached by their narrow ends to the crop. 

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



