142 EEPORT OF COMMISSIONER OF FISH AND FISHERIES. 



NEMASTOMA. 



(From vrifia, a thread, and arofia, a mouth.) 



Fronds gelatino-carnose, compressed -cylindrical or plane, dichoto- 

 mous or subpinnate, composed of an axial layer of densely woven longi- 

 tudinal filaments, from which are given off short, lateral, dichotomous, 

 fastigiate filaments, which are united by a gelatinous substance to form 

 a peripheral layer; tetraspores cruciate, borne in the peripheral layer; 

 antheridia borne on the superficial cells of the periphery; cystocarps 

 (favelhie) buried in the peripheral layer, spores escaping by a narrow 

 opening between the peripheral filaments. 



A genus comprising not far from a dozen species, which inhabit principally the 

 warmer waters of the globe, the genns being particularly well represented in Aus- 

 tralia. Tbe fronds of the different species vary from only slightly compressed and 

 linear to broad and palmate, and in G. marginifera the frond resembles in shape that 

 of Ehodymenia palmata. The substance is rather gelatinous and the microscopic struc- 

 ture resembles very closely that of the fronds of some of the Nemalieas. The fruit of 

 jV. marginifera is described by Bomet, in Notes Algologiques, as being a true favella like 

 that of CaUithamnion. The geuus is generally placed near Gloiosiphotiia, and, like that 

 genus, closely connects the Ceramiew with the Cryptonemew. 



~N. (?) Bairdii, Farlow, Proc. Am. Acad. Arts and Sciences, 1875, 

 p. 351. 



Fronds purplish-rose colored, gelatinous, four inches long, one inch 

 wide below, vermiform, once or twice dichotomously divided, axils acute, 

 apices attenuated ; tetraspores cruciate, borne on the tips of the peri- 

 pheral filaments; cystocarps 



Washed ashore at Gay Head, W. G. F. 



A very rare species, of which only a single specimen is known. It was found on the 

 beach near the light-house at Gay Head, Mass., in company with Scinaia furcellata, in 

 August, 1871. The specimen was a fragment, without the base of the plant, but 

 with abundant tetraspores, which were borne on the tips of the peripheral filaments. 

 In the absence of cystocarpic specimens the genus cannot be ascertained with cer- 

 tainty, and botanists who visit Gay Head, should seach for the plant by dredging off 

 the Devil's Bridge in five to ten fathoms. The specimen collected was at first sup- 

 posed to be a portion of a broad specimen of Nemalion purpureum, a species not yet 

 known on our coast. The peripheral filaments are loosely united together by a gela- 

 tinous mass, as in the subgenus Gymnoplrfceaoi Agardh. 



Suborder DUMONTIE^E. 



Fronds tubular, branching or proliferous; cystocarps immersed in 

 the frond, composed of a single mass of irregularly placed cells, similar 

 in most respects to those of the Cryptonemiece. 



A small suborder, included by Harvey in the Cryptonemiew. The development of the 

 cystocarps is not well kuown, and on our coast there is no material to be obtained for 

 the study of the suborder. The common Dumontia filiform is of Northern Euro pe is 

 wanting with us, and the genus Halosaccion, of which we have one representative, 





