GENUS TORQUATELLA. 621 



as here maintained is further afforded by the marked sedentary and vegetative 

 mode of growth exhibited by so large a proportion of its members, and yet more 

 noticeably with reference to the phenomena of reproduction as elicited by the light 

 of recent investigation. In this last-named connection it has been abundantly 

 shown that the process of conjugation or genetic union is accomplished through the 

 complete and permanent fusion of two independent zooids, as obtains among the 

 lower sections of the Flagellata and unicellular Protophytes, and which thus differs 

 essentially from the temporary union only of the sexually matured zooids which 

 occurs amongst the Hypotricha and even many Holotricha, and among which, con- 

 sequently, a far nearer approach is made to the typical mode of sexual concourse 

 that subsists among the higher zoologic groups. 



A tabular form of the family and generic groups of the Peritricha, as delimited 

 in this volume, is given overleaf. 



Fam. I. TORQUATELLID-ffi, S. K. 



Animalcules free-swimming, illoricate, more or less ovate ; the anterior 

 ciliary wreath replaced by a membranous extensile and contractile collar- 

 like structure, which is perforated centrally by the oral aperture. 



The relegation of the single type included in this family group to the Peritricha 

 is effected with some diffidence, it possessing, perhaps, an equal claim for recog- 

 nition as the representative of a new and distinct order. Regarding, however, 

 the terminal frill or collar-like membrane as an incipient or only partially developed 

 fringe of cilia, its affinity to the more ordinary members of the section in which it is 

 here placed is apparent. A similar though at the same time transitory assumption 

 by the adoral cilia of a membraniform character is especially alluded to in this volume 

 in the case of Stentor and Aspidisca, while in many Hypotricha, Heterotricha, and 

 Holotricha such a membrane permanently fills the place otherwise occupied by the 

 adoral or pre-oral fringe. On the other hand, the membraniform collar of Torquaiella 

 may perhaps be regarded as homologous with the umbrella-like peristomal mem- 

 brane of Codondla, or indeed as an exaggerated development of the peristome of 

 such a typical Peritrichan as Vorticdla patdlina, as represented at PI. XXXIV. 

 Fig. 22. 



GENUS I. TORQUATELLA, Lankester. 



Animalcules free-swimming, more or less ovate, entirely devoid of cilia, 

 but possessing at the anterior extremity a projecting plicate membranous 

 frill, by the more or less vigorous expansion and contraction of which 

 motion through the water is effected, and food-particles brought within 

 reach of the mouth ; oral aperture situated within the centre and at the 

 base of the projecting frill, guarded by a tongue-shaped valve or velum. 



Torquatella typica, Lankester. PL. XXXII. FIGS. 32-34. 



Body elongate-ovate, nearly twice as long as broad, rounded posteriorly ; 

 the anterior membranous frill highly expansile, its front margin abruptly 

 truncate or emarginate, its surface obliquely plicate. Dimensions unre- 

 corded. HAB. Salt-water, Mediterranean. 



This remarkable animalcule was met with on one occasion only by Professor 

 E. Ray Lankester at Naples in association with a mass of eggs of Terebella in a 

 decaying state, and fragments of which had been freely incepted. The anterior 



