332 TUFTS COLLEGE STUDIES, VOL. II, No. 3 



morpha are separated, species with uninucleate cells being 

 placed in the latter, those with multinucleate cells in the 

 former ; both being distinguished from Cladophora by special- 

 ized branches of a different type from the original normal fila- 

 ment. This distinction is not here maintained, all species with 

 the specialized branches being included under Spongomorpha t 

 the older name of the two. No such distinction is possible be- 

 tween Cladophora and Aegagropila, and there is quite a possi- 

 bility that Aegagropila forms are often or always stages or con- 

 ditions of true Cladophora species. Aegagropila is therefore 

 not here maintained. 



It has not seemed practicable to arrange the species in sub- 

 genera or sections ; so many species are imperfectly known 

 that any arrangement of this sort would be untrustworthy and 

 misleading. For the determination of a specimen the key will 

 serve as well, while leaving open the question as to which of 

 the characters there used should be regarded as fundamental 

 for classification. In this key the marine and .fresh water 

 species are given separately ; an arbitrary division, but as the 

 key is only for the purpose of determination, and does not at- 

 tempt to indicate affinities, this plan seems justified. The 

 marine species are first given, beginning with the more delicate 

 erect species, then the larger and c arser, and ending with 

 prostrate and matted forms ; they are so varied that it is impos- 

 sible to group them about any few centers ; by bearing in mind 

 that everything here is relative, not positive, it is hoped that 

 the key will be of use to students. The fresh water species 

 follow, falling naturally into two groups ; one arranged about C . 

 frada, the other about C. glomerata ; it may be that these two 

 species should include the others, but for the present it is more 

 convenient to keep them separate. 



KEY TO THE MARINE SPECIES OF CLADOPHORA. 



i. Plants with creeping, matted base. 2. 



i. Plants erect. ~6. 



2. Lower part of filaments 300-350 /x diain. 41. C, intertexta. 



2. L,ower part of filaments less than 300 M diarn. 3. 



3. Erect branches subsimple, much smaller than prostrate filaments. 



38. C. ffozl'ti. 

 3. No sharp distinction between different kinds of filaments. 4. 



