RHODOMELACEAE. 525 



apiculate, 300-350 n long, 90-130 /JL broad, 2-4 times as long as broad, sub- 

 sessile on a very short one-celled pedicel. 



Growing on rocks and on Sargassum, near low-water mark. Type from 

 Eed Bay, St. David's Island (Howe 293, in herb. N. Y. Bot. Gard.). This 

 species is most nearly related to the Adriatic and Mediterranean Dasya rigi- 

 dula (Kiitz.) Ardiss. (which apparently has been sometimes confused with 

 Heterosiphonia Wurdemannl) , and to the European species that currently 

 bears the invalid name Dasya Arbuscula,* but it differs from both in the 

 dichotomo-eorymbose arrangement of its main branches and in the short, 

 broad, pericentral siphons, which commonly appear almost quadrate. Ber- 

 muda specimens have recently been referred, sometimes to D. Arbuscula and 

 sometimes to D. ramosissima Harv. From the latter it differs in its small 

 size, dichotomo-eorymbose habit, mostly shorter pericentral siphons, more 

 rigid, and more divaricately forked branchlets, etc. In its rigid divaricately 

 forked branchlets, the species suggests Heterosiphonia Wurdemanni, but is 

 readily distinguished by the eortication of its main branches and by the 

 spirally alternate instead of distichous ramification. Its nearest Bermuda 

 relative is D. corymbifera J. Ag., from which it is best distinguished by the 

 dichotomo-eorymbose arrangement of its main branches, its shorter pericentral 

 siphons, its more crowded, more divaricately forked, less tapering branchlets, 

 which show little or no tendency to be incurved or falcate at their apices, and 

 by its more sessile, more apiculate stichidia. Apparently endemic. The 

 species is dedicated to Mr. F. S. Collins, the well-known American phycologist 

 and co-author of the recently published treatise on ' ' The Algae of Bermuda. 



Dasya pedicellata Ag. [D. elegans (Mart.) Ag.] is the largest of the 

 Bermudian members of the genus, being commonly from six inches to two 

 feet long, with long unequal irregular branches, which may remain simple or 

 may be again branched. The main axes are mostly J-2 lines in diameter. All 

 parts, with the occasional exception of the oldest, are densely clothed with 

 tufts of dichotomous monosiphonous ramelli 1-4 lines long. The plants are 

 flaccid and are reddish purple or lake-red. Cystocarps conspicuous, urn- 

 shaped, borne on the main branches on pedicels of about half their own 

 length. Tetrasporic stichidia ovoid-rostrate to lanceolate-subulate, often 

 slightly curved, borne on the monosiphonous ramelli. 



Dasya spinuligera Collins & Hervey, resembles small, slender, delicate, 

 much-branched, less villous conditions of D. pedicellata, but most of the mono- 

 siphonous ramelli are borne on rather rigid subulate branchlets, such as are 

 wanting or of rare occurrence in the typical D. pedicellata. And the species 

 differs markedly in the much elongate, cylindric, often clustered stichidia, 

 which are 5-10 times as long as broad. (Phyc. Bor.-Am. 2188.} Endemic. 



Family CERAMIACEAE. 



Ptilothamnion bipinnatum (Collins & Hervey) M. A. Howe (Gymnotham^ 

 nion bipinnatum Collins & Hervey, Proc. Am. Acacl. Arts & Sci. 43: 139. pi. 



* The type of Conferva Arbuscula Dillw., on which Dasya Arbuscula Ag. was 

 based, is evidently a CaUithamnion. 



