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



cessible. The specimens from Monterey, referred to Cladophora 

 cartilaginea, Setchell and Gardner, 1903, prove to belong 

 elsewhere. 



Spongomorpha rhizophora Kiitzing, 1849, p. 418 ; 18553, p. 16, 

 PI. LXXVI, fig. 2, is a doubtful species. 



4. CLADOPHOROPSIS Borgesen, 1905, p. 288. 



Frond filamentous, without distinct axis ; basal filaments 

 prostrate, attached by multicellular holdfasts ; erect filaments 

 with more or less abundant branching, with apical growth ; a 

 branch issuing directly under a cross wall, no wall being formed 

 in the branch until the latter has attained a considerable length, 

 and then normally not at the base of the branch ; branches 

 occasionally arising by aplanospore-like bodies formed in the 

 cell, and pushing out through the cell wall ; cells multinucle- 

 ate, with net-shape chromatophore and many pyrenoids ; repro- 

 duction unknown. 



This genus is practically intermediate between Cladophora 

 and Siphonocladus, showing the close relationship of the Clado- 

 phoraceae and the Valouiaceae. It has the habit of a Clado- 

 phora of the subgenus Aegagropila, but the branches have 

 normally no partition at the base. In this latter respect it 

 agrees with Siphonocladus , but the frond does not originate in a 

 single clavate cell. The secondary branching reminds one of 

 Valonia. We have only one species. 



C. MEMBRANACEUS (Ag.) Borgesen, 1905, p. 288, figs. 8-13 ; 

 Cladophora membranacea Harvey 1858, p. 73 ; Siphonocladus metn- 

 branaceus Vickers, 1908, p. 20, PI. XVII; P. B.-A., No. 225. 

 Fronds densely matted, up to 10 cm. high, the holdfasts of the 

 prostrate filaments large and well developed ; erect filaments 

 about 1 80 /u, diam., with branches at first alternate, later secund ; 

 partitions formed at irregular but usually long intervals, the 

 terminal cell usually many diam. long ; branches often adher- 

 ing by tenacula similar to the basal holdfasts, but shorter ; 

 branches arising from aplanospore-like formation not uncom- 

 mon. Fig. 129 Fla., W. I. 



6. PITHOPHORA Wittrock, 1877, p. 48. 



Fronds filamentous, monosiphonous, branching, branches is- 

 suing from below the top of the cells ; cells cylindrical or 

 swollen, multinucleate, with net-like chromatophore and many 

 pyrenoids ; asexual reproduction by akinetes, terminal or inter- 

 calary in the filaments, formed by the division of a vegetative 

 cell, the upper half forming the akinete, the lower half remain- 



