NEW AND LITTLE- KNOWN BROWN ALG^. 39 



It is quite possible that they occur later in the season than the 

 plurilocular sporangia, for it has been impossible to obtain material 

 later than September 1. Although the vegetative filaments and 

 plurilocular sporangia agree with the description and figures of 

 Reinke's Leptonema, the unilocular sporangia are necessary to prove 

 the identity of the species. 



The plant forms brown, flocculent tufts, 8-12 ram. high on the 

 leaves and stems of Fostelsia palmasformis. See PI. I, Fig. 5 a & b. 

 The vegetative filaments are usually unbranched, though a form 

 now and then occurs with short opposite branches at regular inter- 

 vals (Fig. 6). The cells are not at all constricted at the joints, 

 7-12// broad, above as long as broad, below two to three times as 

 long as the diameter. The plurilocular sporangia are formed by 

 the transformation of any or all the cells of the vegetative filaments 

 except the lower; eight, sixteen, or thirty-two zoospores being 

 formed from one of the mother cells. The species also occurs, 

 occasionally, on mussle shells (Mytilus) in the vicinity of tufts of 

 Postelsias. Collected at Point Lobos, Point Cypress, and Point 

 Pinos. July-September. 



Agr. College, Brookings, S. D. 



EXPLANATION OF PLATE I. 

 HAPALOSPONGiDioN GELATiNosiiM D. A. Saunders. 



Fig. 1. A piece of rock showing thalli, natural size. 



Fig. 2. A part of one of the thalli : a, the longer vegetative 

 filaments; b and b', shorter vegetative filnments; c, hair, xl20. 



Figs. 3 and 3'. Two extreme forms of unilocular sporangia, 

 x450. 



Figs. 4, 4', 4", and 4'", Different stages in the formation of the 

 plurilocular sporangia, x450. 



LEPTONEMA FAScicuLATUM Eeinke. 



Fig. 5. a, a piece of the leaf of Postelsia palmseformis showing 

 tufts, natural size; b, a piece of a stem showing same tufts, natural 

 size. 



