520 



SYSTEMATIC HISTOEY OF THE INFFSOKIA. 



to rightly appreciate its characters and to assign it its proper place, even if 

 it is admitted to he an independent organism. Mr. Carter has lately piih- 

 lished (A. N. H. 1859, iii. p. 10) the opinion that Synura is the " spermatic 

 form" of Volvox or of Sj^hcerosira. (See notes on Sphl^eosiea). 



Synura uvella. — Corpuscles oblong, 

 yellow, capable of extending themselves 

 iko three times their usual length, by 

 means of the extensile tail. The cluster 

 has the form of a mulbeny, and its mo- 

 tion is rolling like that of Volvox Gloha- 

 tor. XX. 29, XX. 30, show a portion of 



a cluster, and the manner in which the 

 tails are inserted in the common enve- 

 lope. This species, along with Si/ncrypta 

 and TJroglena Volvox^ may have often 

 been confounded -^dth TJveJla virescens. 

 Length, exclusive of tail, 1-700" ; dia- 

 meter of cluster from 1-190" to 1-280". 



Genus UROGLENA (XX. 31).— The members of this genus, unlike other 

 Volvocina, possess both an eye-speck and tail ; they live in clusters under a 

 common envelope (lacerna), which is subdivided into cells for the accommo- 

 dation of the several individuals. Self-division takes place simply and equally 

 in these individuals, whilst in their clustering condition. They are placed at 

 uniform distances from each other, attached by their tails, which radiate from 

 the centre. Each monad is furnished with a filament, which projects ex- 

 ternally and gives to the entire group the appearance of being covered with 

 hairs. When the creatures divide, the mantle or lacerna enlarges only, and 

 does not itself undergo fission. The red speck is in the fore j)art of the body ; 

 the tail is filiform, resembling that of Vorticella and Bodo. 



The tail mentioned in the above description is the same as that of Synura : 

 the use of the term is very inappropriate in both cases. It may be that 

 Uroglena should be united with Synura as Dujardin proposed, since the 

 presence of an eye-speck in the former and its absence in the latter is not 

 distinctive; still we know too little of the being which Ehrenberg would 

 call a Uroglena, to come to a decision respecting its affinities and generic 

 independence. 



This genus is another which Mr. Carter would set aside, as he considers it 

 (A. N. H. 1859, iii. p. 10) the same with Sphcerosira, or the " spermatic 

 form " of Volvooo. (See notes on Sph^rosiea.) 



Uroglena Volvox (xx. 31). — Cor- 

 puscles yellow, oblong ; tail extensible, 

 from three to six times the length of the 

 body, and even more ; cluster mulberry- 

 shaped. There is little doubt that single 

 corpuscles of this genus have often 

 been taken for creatm'es of a different 



family. Ehrenberg states that he has 

 observed indi\dduals with two or three 

 colom'ed specks, which he conceives to 

 have been a symptom of approaching 

 self-division. In tm-f Tvater. Diam. ot 

 cluster 1-90". 



Genus EUDORINA. — Has no tail, but possesses a distinct eye-speck, and 

 a simple \ibratory filament anteriorly. Self- division proceeds simply and 

 equally, whilst the corpuscles retain their clustered condition. They are 

 periodically able to cast off their globular envelope (lacerna), and to exude a 

 new one, like certain Annelida. To observe the eye-speck, a power of 300 

 diameters must be skilfully employed. 



Dujardin 's proposition to combine Eudorina with Pandorina has been 

 already mentioned (p. 515), and appears to be a correct one. The assigned 

 characteristic difference between those two genera is worthless; for Pandoiiiia, 

 like Eudorina, has a coloured speck (see p. 157 et seq.). 



Eudorina elegans. — Corpuscles green, 

 globular, never protruding fi^om their cells 

 beyond the common envelope. Stigma 

 sparkling red. The clusters, which are 

 of an oval or globular form, contain 



generally from 30 to 50 individuals, and 

 never less than 15. Motion revolving. 

 Fig. 47 exhibits the filaments extended, 

 and the bodies of the animalcules within 

 the lacerna (i. e. the " common enve- 



