402 GENEEAL HISTOfiY OF THE IXFrSORlA. 



retractile appendage surmoimting the trochal disk. In Brachionns urceolaris 

 (XXXIX. 15, 16), straight non-vibratile cilia occur between the ciliated lobes 

 of the rotary organ ; and in Polyarthra there are fleshy tentacular appendages, 

 which Siebold suggests are antennae or feelers. The 2-4 styHform processes 

 of Synchceta, Ehrenberg supposed to possess prehensile powers. In Cono- 

 cJiUiis, four processes, terminated by bristles, project from the ciliary disk ; 

 in Melkerta are two cuiwed hooks. To some of these appendages, and to 

 others about the head, various fanciful names have been given, borrowed 

 mostly from remote resemblance in appearance, situation, or function to parts 

 existing in the higher animals. For instance, on each side of the head of 

 Notommata aurita, N. Copeus, and Diglena aurita, a lobe of the trochal disk is 

 more elevated or elongated than the rest, and has received the appellation of 

 "ear" or " auriciilar ; " the 2-4 supplementary processes of the head of 

 Polyarthra (XXXYIII. 30 a, h) have been called " horns," — a name applied 

 to a similar projection in other Rotatoria. 



In Stephanops a prominent scale-like process of the head is kno-\vn as the 

 " hood " (XL. 8-10). Mr. Gosse speaks of a projecting spoon-shaped lobe 

 in MeVicerta, covered with cilia, as the chin, which "Williamson recognizes a3 

 a '•' fifth lobe " of the wheel organ (XXXYII. 17 c). The latter writer, again, 

 adopts from Schiiffer the appellation of " lips " for two hook-like appendages 

 of the head of Melkerta, and fui'ther describes, on each side the oral aperture, 

 two projecting " flattened lobes, with ciliated margins continuous with those 

 of the ' chin,' which obviously assist in directing the food into the iDesophagus." 

 Lastly, Ehrenberg fi-equently employs the term " frontal region " or forehead, 

 to signify the anterior surface of the head. 



Certain tubular -looking processes, freqiiently fiunished with a pencil of 

 fine non-vibratile cilia or bristles at the extremity, have gained particular 

 consideration owing to the functions assigned them by Ehrenberg and others. 

 They protrude from the head near the trochal disk, and more commonly from 

 the neck, as is seen in Rotifer, Philodhui (XXXYIII. 20), Brachionns 

 (XXXYIII. 15 ; XL. 11), Actinurus, in EucJilanis Lynceus, in MeJicerta 

 (XXXYII. 17), in Salpina mv.cronata, in Notommata davulata, N. Myrraeleo, 

 N. Sieboldii, and other species. In aU the above the appendage is single, 

 but in TuhicoJaria and MeJicerta (XXXYII. 11 cl) it is double. In Calli- 

 clina Ehrenberg mentions a thickly- ciliated proboscis, apparently retractile, and 

 attached to the trochal disk ; occasionally, instead of tenninating by a bunch of 

 setae, these processes have a horn-like prolongation, as in Notommata centrura 

 and N. Copeus. The short conical elevations of Synchceta and Polyarthra 

 belong to the same category with the tubular variety. A long flabeUiform 

 process occurs in connexion with one of the ciliary lobes of Floscularia, which 

 is often called a proboscis, and supposed to be tubular. Ehi-enberg has as- 

 signed two different appellations to these tube-like appendages. At one time 

 he calls such a process a sjmr {'' calcar "), and imagines that it subserves the 

 generative process as an intromittent organ ; at another he represents it as 

 a respiratory tube (siphon), through which water may enter to act on the 

 vibratiLe tags (gills) seen within the abdomen. The former view has found 

 no supporters, and is entirely set aside by oiu- present knowledge of the 

 reproductive act of the Rotatoria ; the latter has been admitted by several, 

 among others, by Siebold, although recent researches now render it untena- 

 ble, and demonstrate the analogy of these appendages with the feelers (an- 

 tennae and palpi) of Entomostraca and other Crustaceans. Dujardin seems 

 to have been the fii'st to suggest the analogy mentioned. Referring to these 

 processes and to others less considerable, terminated by a bundle of stiff ciha,^ 

 he observes that they recall, to some extent, the palpi and antennae ot 



