860 APPENDIX. 



surface by the ventral groove in such a manner that the body as seen in optic 

 transverse section presents a kidney-shaped aspect : cihary girdles eight in number, 

 disposed somewhat obhquely ; flagellum as long or longer than the body, issuing 

 from the ventral region of the apical cUiary girdle, distinctly thickened at its 

 proximal extremity ; endoplasts four in number, distributed in rectilinear order 

 through the central region of the body ; endoplasm coloured pink, enclosing scat- 

 tered apparent trichocysts, identical in structure with the thread-cells or nematocysts 

 of the Ccelenterata. Length of body 1-700". Hab. — Saltwater: Baltic Sea. 



As demonstrated by Bergh, the members of the genus Polykrikos must be referred 

 to the Ciho-flagellate order of the Infusoria, their distinction from the more ordinary 

 Peridiniidae consisting only in the greater numerical development of the equatorial 

 ciliary girdles. The so-called seta issuing from the oral region, as interpreted by 

 Biitschli, is distinctly proved to be an elongate flagellum, the thickened basal region 

 only of which appendage was recognized by the last-named authority. The apparent 

 second seta developed near the first, as reported by Biitschli, of Polykrikos Schwartzii 

 (see Vol. I. p. 508 and PI. XXVII. Fig. 8), not improbably represents the basal region 

 of a second flagellum, developed as a preliminary to the phenomenon of transverse 

 fission. Polykrikos auriailaria differs from the last-named tj'pe in its more minute 

 dimensions, in the smaller number of ciliary girdles, these never exceeding eight, 

 and four being the number of the subdi\dded zooids, in the larger number of 

 endoplasts, and in the pinkish hue of its endoplasmic substance. The so-called 

 trichocysts, irregular in both number and position, reported of this species also by 

 Bergh, agree precisely with the nematocysts of the Ccelenterata, and are most 

 probably incepted with its usual food-material. The fact recorded by its discoverer, 

 that the vegetable colouring substances chlorophyll and diatomin are never present 

 in this form, indirectly points to its carnivorous habits, and further substantiates the 

 author's interpretation of these problematic structures. 



Cl.ass Ciliata. 



Benedenia elegans, Fcettinger. — Body elongate subcylindrical, somewhat 

 enlarged at the anterior extremity ; cilia distributed over the entire surface ; 

 muscular fibrilte developed upon a spiral plan throughout the length of the body ; 

 contractile vesicles not detected ; endoplast band-like or represented by numerous 

 homogeneous granular rods or spheres, rendered visible only with the assistance of 

 reagents ; movements complex, either forwards or rotary upon its axis, the body 

 frequently folded upon itself. Multiplying by segmentation, a portion towards the 

 hinder extremity of the body becoming first separated by a transverse groove, which 

 is again divided into as many as eight nodular segments which are detached 

 separately from the parent. Length 1-25". 



Hab. — Endoparasitic within the renal organs of the Cephalopod Sepia elegans. 



This type, which is referred by Fcettinger to the Opalinidae,* would appear in 

 many respects to resemble the Termite parasite Duimympha gracilis of Leidy, de- 

 scribed and figured at p. 555 and PI. XXVIII. Figs. 21-24. A second species, having 

 a more marked development of the cilia in the anterior region, inhabiting the renal 

 organs of the common Octopus, Octopus vulgaris, receives from the same authority 

 the name of BeiuJenia coronafa. An ovoid Infusorium without mouth or digestive 

 tube, having a similar holotrichous plan of ciliation, a distinct layer of muscular 

 fibrillje below the surface of the cuticle, length about 1-250", and inhabiting the 

 liver of Sepiola rondelctii, is distinguished by M. Fcettinger by tl-.e title of Opalinopsis 

 sepiolce, and a very similar type, derived from the hver of Octopus tetradrrhus, as 

 Opalinopsis octopi. 



Chilodon propellens, Engelmann.t — Closely aUied to C. cucullulus, but of 

 more slender form and with a rounded posterior extremity ; swims in circling paths ; 



* ' Bull. Acad. Royal Belgique,' and 'Archives de Biologic,' Band ii., iSSl. 

 t Notice in 'Nature,' p. 303, July 24th, 1S79. 



