COLLINS. THE ALGAE OF JAMAICA. 251 



Dictyerpa Jamaicensis n. g. & sp. Frond filiform, 1-3 mm. diam. 

 up to 2 dm. long ; consisting of two layers of cells, an inner layer of large, 

 colorless, cylindrical cells, about three diameters long, symmetrically 

 arranged; an external monostromatic layer of brown rectangular cells 

 from one to three diameters long, in distinct longitudinal series. Branch- 

 ing di- or trichotomous, with occasional irregularly placed lateral branches, 

 mostly at wide angles, each branch ending in a large, depressed-hemi 

 spherical cell, by whose division the growth of the branch proceeds. 

 Tufts of very fine, rust-colored or colorless confervoid rhizoidal filaments 

 at irregular intervals on the frond. Fructification ? Washed ashore, 

 Manchioneal, July, 1900. P. B.-A., No. 780. 



Though evidently belonging to the Dictyotaeeae, this plant differs 

 from any genus of the family yet described, in having the frond terete 

 throughout. Many Dictyotaeeae have prostrate rooting filaments from 

 which the erect fronds arise, but in all species found in Jamaica this pros- 

 trate growth is quite insignificant in comparison with the plant in ques- 

 tion. It was found washed ashore in two places, in considerable quantity, 

 and in no case shows any indication of fructification, or of producing 

 erect flattened fronds. It may seem hazardous to give it a generic name, 

 but as it is a plant of quite distinct habit, and cannot be now identified 

 with any named form, it seems to require at least a provisional name. 



As washed up on the beach, it appeared like rolled and twisted strings. 

 The dried plant is quite black in color, and under a hand lens shows 

 closely set constrictions, probably due to the large interior cells being of 

 uniform length, and terminating at the same level, as in the frond of 

 Polysiphonia. These constrictions are lost when the frond is remoistened. 



Goniotrichum Humphrey! Collins. On woodwork of wreck, St. 

 Ann's Bay, March 24, 1893, No. 31G, II. P. B.-A, No. 421. 



" Frond filamentous, solid, gelatinous, occasionally forking or dividing 

 into several branches, the terminal portion consisting of a single series of 

 cells ; the older part containing numerous cells, irregularly placed near 

 the surface of the filament ; lateral branches abundant, simple, issuing 

 nearly at a right angle, composed of a single series of cells." This de- 

 scription is copied from the label of P. B.-A., No. 421. 



G. elegans (Chauv.) Le Jolis. Among other algae, on Laurencia 

 obtusa, near Kingston, Duerden. 



Chantransia Saviana (Menegh.) Ardiss. Among other algae, on 

 Laurencia obtusa, near Kingston, Duerden. 



Liagora Cheyneana Harv. Washed ashore, Port Maria, March 17, 

 1893, No. 281 ; Port Antonio, March, 1893, No. 186, II. 



