ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 353 



spirale it is spirally twisted. The ciliary movement seems to go in one 

 constant direction, beginning on the left of the ventral surface. In 

 Gymnodinium there appears to be only one contractile row in the 

 furrow. In PolyhiJcos there are eight furrows independent of each 

 other. The edges of these furrows are interrupted on the ventral side ; 

 the posterior ones continue in a peculiar system of horns and ridces 

 which are either placed close on each other, as on the small ventral 

 side of Dinophysis, or are separated from each other as a ri^ht and 

 left hand division (Protoperidiniiim) ; this entire apparatus serves for 

 limiting the longitudinal furrow. In the other forms either the 

 horns alone persist (Peridinium), or the ridges {Biplopsalis, Ghno- 

 dinium), or both are absent (Ceratium, Gymnodinium.) The Flagellum 

 is inserted either through a wide ventral aperture in the membrane 

 {Ceratium) or through a narrow fissure in the longitudinal furrow, 

 either at the anterior pole (Prorocentrum) or the posterior pole 

 (Amphidinium, according to Claparede and Lachmann) or in their 

 neighbourhood. 



Of the propagation and development of the Cilio-flagellata little is 

 known with certainty. We find fission as well as conjugation. 

 Transverse fission results either in a free-swimming animalcule (as 

 for example in PolykriJcos, in Allman's Perid. uherrimum), or in with- 

 drawal into the old membrane (Perid. tahulafum), or finally in certain 

 cysts, which are either round {Glenodinium cinctum, Gymnodinium 

 according to Stein) or have peculiar, strange (horned) forms {Perid. 

 tahulatum according to Stein). Conjugation is especially shown by 

 Stein in Gymnodinium pulvisculus ; but several of his statements, the 

 author thinks, require a complete revision. 



Under the head of " Phylogeny " the author endeavours to unravel 

 the relationship of the organisms, even for each genus and species. 

 The results of such an attempt could not be very definite, for, as he 

 himself says, we have not the necessary paleeontological evidences and 

 consequently the intermediate forms are wanting that have existed in 

 past times. The author's six genealogical trees can therefore only be 

 taken for what they are worth, that is as a representation of the more 

 or less intimate relation which we can recognize between certain 

 forms. It is, however, a clever and convenient method of expressing 

 one's views of the affinities.* 



According to the author, the Flagellata form a point of departure 

 from which are developed phylogenetically (diverging on different 

 sides), the Noctilucce, Ehizopoda and Cilio-flagellata. The oldest 

 forms of Cilio-flagellata were the Adinida, of which only one living 

 species {Prorocentrum) is now known. They acquired small cilia, and 

 a bilaterally asymmetrical form. There later appeared the ciliary 

 apparatus, at first posteriorly and then anteriorly limited by the 

 ridges of the membrane, so that a transverse furrow was formed 

 (Dinifera) which was originally on the anterior margin {Dinophysis, 

 Amphidinium) ; then the flagellum was removed from its primary 

 position, posteriorly, whereby a longitudinal furrow was formed, at 

 first confined by a complicated apparatus of ridges and horns. Still 

 * Cf. Arch. Sci. Phys. et Nat., vi. (1S81) pp. 402-4. 



