1919] Setchell-Gardncr : Myxophyceae 21 



carpa as a marine genus also to be included. The presence of goni- 

 dangia, "coccogonia, " whose contents break up into from four to many 

 gonidia, "eoiiidia," is especially mentioned as characteristc. li'. liow- 

 ever, it is to be taken as established that gonidia also occur in a large 

 number of genera both of the Coccogonales and Hormogonales, this dis- 

 tinction will prove unsatisfactory. As remarked under Chroococcaceae, 

 some, if not all, of these cases need substantiation and more careful 

 stud}', especially those credited to various Hormogonales. It seems 

 most likely that they may occur in Gomphosphaeria and this genus has 

 been transferred on this account to the Chamaesiphouaceae, since it 

 also resembles, in the shape of its cells, Dermocarpa. Gonidia have 

 occurred also in plants resembling closely Gloeoc<ipsa crcpidinimi 

 Thuret, but which have been placed below, equally satisfactorily, 

 under Pleurocapsa. Most of the Chamaesiphouaceae are epiphytic 

 and many are attached by a more or less differentiated basal portion, 

 but these characters, either separately or taken together, seem suf- 

 ficient to distinguish this family from the Chroococcaceae. 



Key to tiik G i:\kka. 



1. Cells not in filaments 2 



1. Cells in filaments 5 



2. Cells solitary or in layers 3 



2. Cells in floating globular masses 13. Gomphosphaeria (p. 49) 



3. Layers more or less uniform 4 



3. Layers irregular or complex 10. Pleurocapsa (p. 36) 



4. Cells destitute of vegetative division 8. Dermocarpa (p. 21) 



4. Cells dividing in 2 planes 9. Xenococcus (p. 30) 



5. Oonidangia basal at surface of substratum 11. Hyella (p. 40) 



5. Oonidangia terminal above surface of substratum 12. Radaisia (p. 45) 



8. Dermocarpa Crouan 



Cells most frequently epiphytic, spherical, ovoid, pyrifonn to 

 narrowly cuneate, occasionally existing singly but mostly aggregated 

 into dense clusters, often so crowded as to distort their form; proto- 

 plast homogeneous or finely granular, with blue-green, brownish or 

 violet color; cell wall comparatively thick, mostly homogeneous, 

 hyaline ; no multiplication by vegetative cell division ; reproduction 

 wholly by the formation of gonidia. 



Crouan, Note sur quelques algues marines nouvelles, 1858, p. 70. 



Dermocarpa was founded by the brothers Crouan (1858, loc. cit.) 

 on Z>. violacea, a species growing on fragments of crockery at Brest. 

 Nothing further seems to have been done in the study of the genus 



