596 ORDER HETEROTRICHA. 



step towards the genus Follictilaria, in which the bilobate shape of this area forms 

 a leading characteristic. It was discovered, in February 1877, * n some abun- 

 dance on the vacated polyparies of polyzoa and hydroid zoophytes obtained from 

 the Westminster Aquarium. Being at the time specially occupied in investigating 

 certain more minute flagellate Infusoria, the author unfortunately neglected to note 

 the form and position of the contractile vesicle or any reproductive data. The 

 brief description and figure here given will doubtless, however, suffice for its re- 

 identification and as a basis for a future more exhaustive examination. 



Stentor pediculatus, From. PL. XXX. FIG. 5. 



Body trumpet-shaped when extended, elongate-ovate or fusiform when 

 contracted ; colour clear brown ; width of the expanded peristome equal to 

 about one-quarter of the length of the entire body ; the area enclosed within 

 the peristome-border ornamented with numerous raised papillae, the 

 apex of each of which gives origin to several long, fine, hair-like setae ; the 

 posterior and adherent extremity of the body divided into six digitiform 

 prolongations, out of each of which four similar fine hair-like setae take 

 their origin. Length of extended body 1-120". HAB. Fresh water. 



Doubtful Species. 



The form temporarily referred to this genus by Stein under the title of Stentor 

 cucullus, is synonymous with the Vorticella cucullus of Miiller. It is a large, bright 

 yellow, salt-water variety, so closely corresponding in shape and size with Stentor 

 Roeselii that Stein would have referred it without hesitation to that species had he 

 encountered it in fresh water. In consideration, however, of its marine habitat, he 

 thinks it desirable for the present to regard it as a distinct type. In the only 

 example observed by this authority the endoplast was long, cord-like, and of 

 undulating outline. 



Out of the nine varieties of the genus Stentor introduced by De Fromentel in 

 his ' Microzoaires ' as hitherto undescribed species, his S. pediculatus appears to be 

 the only one with which are included characters sufficiently distinct to warrant its 

 recognition as a new and independent form. In all other cases the diagnoses 

 and figures given embody no character which can be cited as distinguishing them 

 from those earlier known varieties made familiar to us through the researches of 

 Ehrenberg, Stein, and Claparede and Lachmann, while in almost every instance the 

 diagnosis and figure given represent the animalcule in that free-swimming and semi- 

 contracted condition in which it is almost impossible to discriminate between closely 

 allied species. Briefly examined, the Stentor roseus of this author, with its spherical 

 nucleus and bright rose colour, is apparently referable to S. igneus Ehr., his 

 S. fuscus to S. niger Ehr., S. fimbriatus to S. Rceselii prior to fission; while his 

 S. aneeps, S. elegans, S. nanus, S. deformis, and S. albus appear to represent merely 

 young or imperfectly developed conditions of other previously established forms. Of 

 this, in fact, De Fromentel in several instances expresses himself prepared to admit 

 the probability. In all De Fromentel's figures relating to the genus Stentor, the 

 oral aperture is wrongly delineated as being circumscribed by a continuation of the 

 right-hand limb of the peristomal border. 



GENUS II. FOLLICULINA, Lamarck. 



Animalcules highly elastic and contractile, secreting a horny sheath or 

 lorica, to the inner wall of which they remain affixed by their posterior 

 extremity ; peristome-field embracing the entire anterior border, produced 



