vni DISC 203 



and the trochus is a horseshoe-shaped ridge, with its ends dorsal 

 and raised into prominent knobs. The margin of the funnel 

 is in Flosculariidae (Fig. 115) usually lobed, and furnished either 

 with exceptionally strong cilia, or else with very long bristles 

 which are usually passive. However, by the retraction of the 

 lobes that bear them they are clasped together like casting-nets 

 to enclose prey brought into the funnel by the action of the 

 trochal cilia. An external ring of cilia in Floscularia mutahilis 

 and F. jpelagica serves for swimming. In Apsilidae the margin 

 of the disc bears neither cilia nor bristles, but is either simple 

 and ring-like, or is produced into tentacles (Fig. 112, C). The 

 oral funnel is probably represented in Flosculariaceae by the con- 

 tinuation of the small central mouth into a ciliated tube (Fig. 

 115, C, tf), open below, and hanging freely down into the crop. 



In all other cases the mouth is displaced, and lies in the 

 groove and on its ventral side (except in Conochilus, where it is 

 dorsal, Fig. 108, 5). In the Bdelloida the disc is prolonged into 

 two great lobes like kettle-drums, round the posterior, external, 

 and ventral edges of which run the trochus, cingulum, and cili- 

 ated groove (Fig. 108, 2). All three are interrupted behind in 

 the median line ; ventrally the groove widens into the oral 

 funnel, the cingulum is continued into a sort of spout-like lower 

 lip (Fig. 109, C, D, I), and the trochus is absent. The body is 

 prolonged dorsally above the lobes into a two-jointed proboscis, 

 ending in a ciliated cup overhung by two dorsal flaps : this we 

 regard as a detached portion of the wreath. 



This " Bdelloid " type of wreath occurs also in Scirtopoda 

 (Fig. 117), and in the Ploimal genera Triarthra, Pterodina, and 

 Pompholyx. A simpler wreath of essentially the same type occurs 

 in Asplanchnaceae and Melicertaceae ; the disc is not prolonged 

 into drum-shaped lobes, but is thin at the rim, where it bears 

 the triple ciliated zone, interrupted on the dorsal median line and 

 depressed ventrally into the oral funnel. In the Melicertidae, 

 moreover, the disc is widened into a great plate-like extension, 

 often beautifully lobed ; and in many of the species a ciliated 

 cup lies ventral to the lips, and is connected with the groove by 

 a short ciliated channel on either side (Figs. 108, 4, and 116). 

 Even the simpler wreath of Asplanchnidae is complicated by 

 stronger lobes on either side bearing vibratile styles. 



The most complex discs are found in Ploima, especially in 



