322 PEOTOCOCCE^. 



repeated, and hence arise so many concentric vesicles en- 

 closing the small globule in the centre. 



" Frequently the globule, having shrunk from its proper 

 envelope, is divided into half, and each half, having shrunk 

 from its investing vesicle, again is divided into two parts, and 

 this occurs many times in succession. At length, the vesicles 

 being torn or converted into mucus and absorbed, the glo- 

 bules themselves formed by division are poured out into the 

 common mucous substratum. At other times the primitive 

 globules, or more frequently the internal substance of the 

 second, the usual division being suspended, passes into very 

 minute granules, and the involucre of the globule itself con- 

 verted into mucous substance, gives birth in the same man- 

 ner to new globules. The frond in the beginning indeed 

 definite, nevertheless speedily becomes confluent, and inde- 

 finitely expanded. This genus, therefore, differs only from 

 Coccocldoris in the division of the globules, which likewise 

 manifests an affinity to Pleurococcus." Meneyhini. 



The species included by me in the genus Hcematococcus 

 admit of division into three subgenera. They embrace also 

 the genera Microcystis and Pleurococcus of Meneghini, to dis- 

 tinguish which genera I can find no satisfactory character. 



First Subgenus. Globules appendaged, that is, each termi- 

 nates or is imbedded in the extremity of a distinct mucous 

 prolongation, the mass of the plant being formed princi- 

 pally of these mucous prolongations. 



The term Ouracoccus might be applied to the species of this 

 subgenus. 



a. Mucous prolongation plain. Granules invested with a 

 single vesicle. 



1. HCEMATOCOCCUS ALLMANI HttSS. 



Plate LXXX, Fig. 3. 



Char. Globules elliptical, large, blood-red, surrounded by a 

 single diaphanous margin. 



