1919] SetcheU-Gardner : Myxophyceae 25 



sions and which reproduce exclusively by gonidial formation. These 

 are Cyanocijstis Borzi (1882, p. 314), Dermocarpa Crouan (1858, 

 p. 70), Clastidium. Kirchner (1880, p. 195), Chamaesiphon A. Br. and 

 Grun. (ef. Rabenhorst, 1865, p. 148), and Godlcwskia Jancz. (1883, 

 p. 227). Kirchner separates the first three genera from the last two 

 because of tlie simultaneous division of the whole protoplast of the 

 gonidangium into gonidia, whereas in the last two genera the gonidia 

 are abstricted successively from the apex of the gonidangium, the 

 basal portion always remaining sterile. Forti adopts this arrangement 

 except the statement as to the simultaneous division of the protoplast. 

 It is necessary to modify Kirchner 's statement in regard to the 

 simultaneous division of the protoplast in Dermocarpa since we have 

 found ill several species that the gonidia result from successive divi- 

 sions in different planes. This condition is notably true of D. protea 

 S. and G. A further exception to the statement of Kirchner must be 

 made in D. Leihlemme (Reinseh) B. and Th. and in D. stiff lUta S. and 

 G., in that only a portion of the protoplast of the gonidangium is con- 

 verted into gonidia, the basal portion in each species uniformly remain- 

 ing sterile. There is but little likelihood of confusing Dermooarpa 

 with either Chamaesiphon or Godleivskia, on account of their cylin- 

 drical shape, and method of formation and liberation of gonidia, or 

 even with Clastidiioii, which is narrow and c^dindrical and possesses 

 a seta at the outer end, but in attempting to place a species like D. 

 sphaerica, or D. sphaer&idea S. and G., the question arises as to which 

 genus, Dermocarpa or Cyanocystis, if both of these are to be consid- 

 ered valid genera, should receive them. Tlie method of escape of 

 gonidia in D. sphaeraid^ea has not been determined, but in D. sphaerica 

 the whole wall of the gonidangium dissolves and the group of gonidia 

 is left free in position. The only distinction between Cyanocystis 

 and Dermocarpa, as brought out l)y both Kirchner and Forti, is that 

 of the method of escape of gonidia. In the former they escape by a 

 circumscissile rupture and in tlie latter by a dissolution of the apex 

 of the gonidangium. If the method of escape of the gonidia is to be 

 taken as sufficient for generic distinction, it will be necessary to create 

 another genus for D. sphaerica which does not conform to either of 

 the above methods. It seems preferable in this case to refrain from 

 extending the number of genera, but to reduce it rather, and since 

 Dermocarpa is the older genus to adopt that to receive our species, 

 and reduce Cyanocystis in ease furtlier study makes it necessary or 

 desirable. 



