1919] Setchell-Gardncr : Myxophyceae 23 



Growing on Rhodochorton Rothii in moist, shaded places along 

 high-tide level, or even above. Moss Beach, San Mateo County, Cali- 

 fornia. The above locality is the. one from which the type material 

 has been obtained, but the plant has been observed growing on the 

 same host at a number of different localities along the California coast. 



Setchell and Gardner, in Gardner, New Pac. Coast Alg. II, 1918, 

 p. 438, pi. 37, fig. 21 ; Collins, Holden and Setchell, Phyc. Bor.-Amer. 

 (Exsicc), no. 2253. 



Dermocarpa hemisphaeriea is a somewhat aberrant plant. The 

 individuals are small, mostly solitary, and multiplication is wholly 

 by means of gonidia. In size and distribution on the host it resembles 

 Xenococcus in the early stages of development of that genus, but 

 differs from it in not having increase by means of vegetative cell 

 divisions. In its solitary habit and method of reproduction it resem- 

 bled Cyanocystis, but differs from that genus in its method of escape 

 of gonidia. Those of D. hemisphaerica escape through a small open- 

 ing at the apex of the gonidangia, and those of Cyanocystis escape by 

 means of a circumscissile splitting of the gonidangia. It seems more 

 nearly to fulfil the requirements of the genus Dermocarpa, as now 

 generally understood than of any other genus of Chamaesiphonaceae. 

 It differs, however, from previous conceptions of species of that genus 

 ill tlic iiictliod of the formation of gonidia. They are formed in this 

 species by successive divisions of the contents of the gonidangia, those 

 in earlier described species being formed bj- simultaneous division. 

 In this respect it is like some species of Pleurocapsa as well as more 

 recently described species of Dermocarpa. 



Dermocarpa hemisphaerica is commonly associated with Chloro- 

 gloea conferta (Kuetz.) S. and G. and Dermocarpa suffulta S. and G. 

 The early stages of the development of D. hemisphaerica and D. suffulta 

 are very similar to each other, but they soon differentiate into their 

 characteristic shapes, and at maturity are very readily distinguishable. 

 Chlorogloea conferta is very frequentlj^ also present and in such 

 abundance as to completelj^ cover up the other two species, hence 

 this condition along with the presence of diatoms and other foreign 

 material, has made the separation of these forms somewhat difficult. 

 The type material is comparatively free from foreign substances and 

 the plants of D. hemisphaerica and D. suffulta are both fruiting, are 

 abundant, and comparatively free from Chloroyloea. This condition 

 has made it possible to trace the life history of each of these three 

 species, establishing beyond a doubt that they are not to be considered 

 stages in the life history of a single form. 



