Dr. F. Cohn on a new genus of the family 0/ Volvocinese. 331 



by the grouping of the primordial-cells. If, as the meaning of 

 the words indicates, the eight separate cells of Werneck^s Ste- 

 phanoma composed a sphere, Stephanoma would agree with Bo- 

 tryocystis Volvox, inasmuch as the latter genus, furnished with an 

 untenable diagnosis by Kiitzing, has been applied by Al. Braun 

 to an actually existing being composed of eight (rarely four or 

 sixteen) segments of a sphere surrounded by an envelope pretty 

 closely investing them (Ueber Verjungung, &c., 170*). 



Considering the impossibility of clearing up the relation of 

 Trochogonium and Stephanoma to our form, from the materials 

 to which I have access, it seemed to me requisite for the interests 

 of science to regard the latter, for the time at least, as a pecu- 

 liar new genus, and to apply a special name to it. I propose for 

 this Stephanosphaera (wreath- globe), to combine in one word the 

 characteristics of the genus, the wreath of primordial -cells and 

 the spherical form of the envelope. Since, moreover, our form 

 has been found in the two stations at present known, in the 

 same way, in rain-water accumulated in hollows of stones, with 

 Chlamydococcus pluvialis, and, concluding from the rarity. of its 

 occurrence, localities of this kind seem to be characteristic gene- 

 rally for the species, I shall assign to it the specific name of 

 Stephanosphcera pluvialis. ''a bolko ad 



<e|[¥. On the Systematic Position of the Volvocinese in generally 



* *rhe decision of the question whether Step hanosphar a pluvialis 

 is to be placed in the animal or the vegetable kingdom is more 

 difficult than the determination of the natural family to which 

 it belongs. It coincides with the general discussion whether the 

 Volvocinece as a whole are to he regarded as plants or animals. 

 The solution of this question is not only of great importance in 

 a general point of view, but on it is essentially dependent the 

 manner in which we have to interpret the conditions of organi- 

 zation observed in Stephanosphcera. 



The earliest observer of the genera belonging to the Volvo- 

 cinea did not hesitate to regard the persistence and variety of 

 their movements, which never seemed interrupted by an act of 

 germination, as a proof of their animal nature. 0. F. Miiller 

 already detected in Gonium pectorah almost all the details which 

 investigation has reached since (Kleine Schriften, 1782, 15), 

 especially that the entire organism is composed of a great num- 

 ber of separate animalcules held together by a common shield. 



/^* In most works Botryocystis Morum is spoken of as a young form of 

 Pandorina, and it was figured as such by Ehrenberg j but I have not been 

 able to demonstrate any genetic connexion in the developmental history of 

 the two genera. ' ju*inv 



