824 ORDER TENTACULIFERA-SUCTORIA. 



granular protoplasmic crest is developed in a spiral fashion around the central shaft 

 of the tentacle. 



Hemiophrya gemmipara would appear to enjoy a relatively cosmopolitan dis- 

 tribution, having been met with by Hertwig at Roscoff, by Lieberkuhn in the 

 Grand Canal at Venice, and by Maupas in the vicinity of Algiers, while the 

 author has collected it in considerable abundance in the Channel Islands and on 

 the Devonshire, Cornish, and North Wales coasts. Among certain of the examples 

 derived from the last-named locality in August 1881, it was observed that the 

 embryos produced by gemmation from the anterior border of the animalcule's body 

 were of an irregular pyriform contour, and provided with short tentacles in addition 

 to, or in place of, a more or less conspicuously developed ciliary covering. A 

 somewhat similar observation has been made by M. C. Robin in connection with 

 specimens gathered at Con9arneau,* but in this case the gemmules were simply 

 tentaculiferous, and are treated of by this authority as an independent form of bud. 

 It would seem more probable, however, that these abnormal gemmules represent 

 instances in which the typical ciliated embryos have undergone their metamorphoses 

 while still adherent to the parent's body, in place of becoming severed from it during 

 the initial or simply ciliate condition, as more usually happens ; this interpretation is 

 substantially supported by the evidence of an intermediate condition, as observed by 

 the author. The successive phases undergone by the detached ciliated embryos 

 during the growth to the adult stalked condition, as observed by M. Robin, are well 

 illustrated at PI. XLVII. Figs. 11-14. It must be mentioned that this investigator 

 proposes to identify this species with the Podophrya Lingbyi of Ehrenberg and 

 Claparede and Lachmann ; as pointed out, however, by M. Maupas,f the last- 

 named type is a normal species of Podophrya, having relatively short capitate ten- 

 tacles only. Prof. E. Perceval Wright has recently reported the present species from 

 the Irish coast. 



Hemiophrya Benedeni, Fraip. sp. 

 PL. XLVII. FIG. 15 AND PL. XLVIII. FIGS. 30 AND 31. 



Body subquadrangular or pyriform, widest anteriorly, tapering towards 

 its point of junction with the pedicle ; prehensile tentacles numerous, about 

 forty in number, their length when extended averaging twice the diameter 

 of the body, their substance spirally fibrillate ; suctorial tentacles short, sub- 

 conical, their extended length not exceeding one-third of the diameter of 

 the body; pedicle quadrangular, from ten to fifteen times the length of 

 the body, its central or medullary substance transversely striate, its external 

 layer transparent and homogeneous ; parenchyma opaque dirty yellow ; 

 contractile vesicles four in number, two developed in each lateral body-half ; 

 endoplast originally horseshoe-shaped, becoming with age diversely ramified, 

 rendered visible only by the action of reagents ; increasing by terminal 

 gemmation. Length of body 1-300". HAB. Salt water. 



This species differs substantially from Hemiophrya gemmipara in the greater 

 relative length and quadrangular contour of the pedicle, in the greater numerical 

 development of the prehensile tentacles, and in the shorter conical contour of those 

 endued with a suctorial function. Examined with a sufficiently high power, it was 

 found that the whole length of the prehensile tentacles, from a short distance from 

 their base, was traversed by a very delicate spiral filament, which, according to 

 M. Fraipont, is developed on the internal surface of the membranous walls of the 



* ' Journal de 1'Anatomie et Physiologic,' 1879. 



t ' Archives de Zoologie Experimentale,' torn, ix., 1881. 



