658 ORDER PERITRICHA. 



ciliary disc convex, moderately elevated ; cilia long and thick, vestibular 

 cleft produced backwards to a considerable distance, giving origin to 

 a conspicuous vestibular seta ; contractile vesicle large, spherical, situated 

 close to the vestibulum ; endoplast band-like, longitudinally disposed. 

 Dimensions unrecorded. HAB. Pond water. 



This species, as described by D'Udekem,* was obtained in some quantity on 

 Myriophylium from the neighbourhood of Brussels ; except for the absence of the 

 mucilaginous investing sheath, its aspect closely resembles the animalcule intro- 

 duced later on under the title of Ophionella picta. Among the examples figured 

 by its discoverer, two zooids, PL XXXIII. Fig. 34, are represented as united 

 by their posterior extremities, the second animalcule having been apparently 

 developed by the process of longitudinal fission, after the manner of the ordinary 

 Vorticellce. 



GENUS II. SCYPHIDIA, Dujardin. 



Animalcules solitary, elongate or pyriform, highly contractile, adherent 

 posteriorly to foreign bodies, through the medium of a specially developed 

 acetabuliform organ of attachment ; surface of the integument often trans- 

 versely or obliquely furrowed ; oral system as in Vorticella. 



Although originally instituted by Dujardin and embodied in Perty's system of 

 classification, Lachmann and Claparede were the first to confer upon this genus 

 its present distinctive import. With the exception possibly of the Scyphidia rngosa 

 of Dujardin, the forms included in it by the two former writers are apparently 

 ordinary Vorticellce which at the time of observation had not developed their charac- 

 teristic pedicles. In their parasitic habits and mode of attachment Scyphidia limacina 

 and S. physarum exhibit a bond of affinity with Spirochona, but are at the same 

 time wanting in the characteristic membraniform spire that so essentially distin- 

 guishes the members of that genus. 



Scyphidia limacina, Lachm. PL. XXXIII. FIG. 32. 



Body nearly cylindrical, tapering slightly at either extremity, annulate 

 transversely ; the posterior extremity truncate, its margin thickened ; peri- 

 stome narrow, not everted ; ciliary disc narrow, considerably elevated. 

 Length 1-360" to 1-240". 



HAB. Fresh water, attached to small specimens of Planorbis. 



Scyphidia physarum, C. & L. 

 PL. XXXI. FIGS. 54 AND 55 AND PL. XXXIII. FIG. 31. 



Body elongate, highly flexible and contractile, evenly cylindrical 

 throughout, coarsely annulate transversely ; peristome having a distinct 

 thickened border ; ciliary disc scarcely exsert, provided with a prominent 

 central umbilicus. Length 1-200". 



HAB. Fresh water, attached to the skin of Physafontinalis. 



This species is readily distinguished from the preceding one by its more 

 attenuate and perfectly cylindrical outline, and also by the larger relative size of its 

 peristome, which is completely evertile, and occupies the entire anterior border. 



* " Infusoires de la Belgique," 'Mem. Acad Royale de Belgique,' torn, xxxiv., 1864. 



