APPENDIX. 857 



author in Vol. I. p. 227 of this treatise under the title oi Acti?iomonas mirabilis and 

 A. pusilla* and is in like manner referable to the there newly established order of the 

 Radio-Flagellata. 



The essential distinctions between these two forms subsist chiefly in the facts 

 that Dimorpha leads an entirely free-swimming condition, never developing a pedicle 

 as in the case of Actinomotias, and possesses two in place of a single flagellate 

 appendage, as obtains in the last-named type. The highest interest attached to this 

 form is connected with the facility with which the metamorphoses from the simply 

 flagellate to the more complex Heliozoidal condition, or the converse, are brought 

 about, such changes, as observed by Dr. Gruber, being effected many times by the same 

 zooid within a single hour. In its simpler biflagellate condition Dimorpha is 

 scarcely to be distinguished from an ordinary member of the genus Heteromita, 

 progression being effected in a similar manner with one flagellum vibrating in 

 advance and the other trailing in the rear. Food-ingestion, as observed of the 

 Heliozoidal condition only, is accomplished at all parts of the periphery. A somewhat 

 doubtful instance of transverse fission was witnessed in which one of the segmented 

 moieties retaining the two flagella swam off as a monadiform zooid, while the other, 

 throwing out pseudopodia, assumed an Actinophrys-like aspect. 



Urceolus (Phialonema) Alenizini, Meresch. — Surface of the body smooth, 

 without striae : neck cylindrical, with the margins abruptly truncated and not turned 

 out. Dimensions unrecorded. Hab. — White Sea. 



This species, though previously figured and described by Mereschkowsky in his 

 ' Studien iiber Protozoen des Nordlichen Russland,' published in the ' Archiv fur 

 Mikroskopische Anatomie,' Bd. xvi., December 1878, was inadvertently passed over 

 by the author when chronicling the associated forms. In his more recent notice of 

 this species ('Annals,' March 1881), Mereschkowsky declares its generic identity 

 with the animalcule upon which Stein t has conferred the title oi Phialotiemacydostoma 

 (see Vol. I. p. 373), but from which form it is readily distinguished by the non- 

 striation of the cuticular surface and the evenly truncate contour of the frontal 

 border. Mereschkowsky further maintains that his name of Urceolus having been 

 bestowed upon the species he discovered, in a yet earlier Russian memoir which 

 appeared in 1877,^ it will have to take the place of Stein's Phialonema in both 

 instances. It is at the same time worthy of remark that in Mereschkowsky's figures 

 and description no indication whatever is given of the existence of the prolonged, 

 posteriorly dilated pharyngeal passage that eminently distinguishes Stein's type, and 

 which is here accepted as affording a diagnostic generic character. 



Anisonema quadricostatum, Meresch. — Body oval, strongly depressed, 

 ornamented on the dorsal surface with four longitudinally disposed ribs or costge. 

 Dimensions unrecorded. Hab. — Salt water : Bay of Naples, Sorrento. 



" The oval body is characterized by its strong depression ; the cuticle, which 

 covers the whole body, is very firm and on the dorsal part it forms at the surface four 

 longitudinal elevations, four ribs, slightly spirally curved. The mouth, which is 

 widely open in the form of a vertical fissure, is very visible on the ventral surface, 

 from which originate two flagella, one of which trained along behind, attains two and 

 a half times the length of the body." § 



Kiinckelia gyrans, Kiinstler. — This species is briefly described by J. 

 Kijnstler || as a fresh-water Noctiluca. The body is capable of elongation, and 

 so enabled to creep about. There is an enormous tentacle which exhibits very 

 active movement when the animal is swimming. Under its cuticle there are two 



* In Vol. I. pp. 226 and 227, and PI. I. Figs. 7, 8, and 10, published in Parts I. and II., October 



and November 1880. 



t ' Infusionsthiere,' Abth. iii. Heft I, 1878. 



j 'Travaux de la Soc. des Naturalistes de St. Petersbourg,' vol. viii., 1877. 



§ "C. Mereschkowsky on some new or little-known Infusoria," 'Annals and Magazine of 

 Natural History,' March 1881. 



II ' Comptes Rendus,' xciii., 1881. 



