of the branches. They are convex but little prominent and fre- 

 quently not distinctly marked, seen from the surface 250 — 300 ;i 

 in diameter, with a single orifice. I have not seen the carpospores. 

 Some other conceptacles resembling the former in shape but smaller 

 probably are those of antheridia. 



The conceptacles of sporangia are unknown. In the solitary 

 fragment of a branch examined I found a couple of overgrown 

 conceptacles, which probably are the latter, as those of cystocarps 

 seem not to grow down into the frond. 



Remark on the synonomy. In Lithoth. p. 35 (63) I remarked 

 that L. racemus auet. appears to be impossible to identify, but 

 that I suppose it to be referrible partly to L. fruticulosum partly 

 to L. crassum. It may be that it in fact also includes the pre- 

 sent species. 



Relation to other species. This plant is closely related on 

 one side to L. fruticulosum and on the other to L. crassum. It 

 differs from the former especially as regards the conceptacles of 

 cystocarps and its coarser structure, but sterile specimens seem to 

 be very difficult to separate. From the latter it distinguishes itself 

 bjr its not or now and then, but very little, roundish thickened 

 ends as well as the shape of the named reproductive organs, which 

 rather resemble those in L. depressum f. Harveyi. 



Loccdity. California, according to Mr. P. Hariot. 



Lithothamnion dentatum (Kiitz.) Aresch. 

 in J. Ag. Spee. Alg. 2, p. 525 ; Spongites dentata Kiitz. Polyp. calcif. p. 33. 

 Descr. et Fig. Lithothamnion dentatum Hauck, Meeresalg. p. 273. t. II, fig. 2 et 



t. V, fig. 2; tab. nostr. fig. 15. 



Remark on the species. Coll. Hariot No. 3. I have not 

 seen any authentic specimen of this alga, but that from California 

 represented fig. 15 so closely coincides with Hauck's description 

 and the figure t. II, fig. 2, that it, no doubt, belongs to the same 

 series of forms. The specimen is nearly 4 cm. in diameter. It 

 is sterile, and the organs of propagation appear to be unknown 

 in this species, which apparently comprehends more than one form. 



Locality. California, according to Mr. P. Hariot. 



