560 GELIDIACEAE. 



2. GRALLATORIA M. A. Howe, gen. now 



Thallus filiform, monosiphonous, the primary filaments dorso-ventrally or- 

 ganized, repent, uncorticated, the ramuli ("short branches") lateral and dorsal 

 in origin, in threes or falsely fives and semi-verticillate, or in opposite pairs; 

 opposite lateral ramuli commonly each forking in its basal cell, the two mem- 

 bers simple or subsimple, few-celled, one of each pair ascending, the other de- 

 flexed and terminating in stelliform or avipedate haptera, giving the primary 

 filaments the appearance of walking on stilts; dorsal ramuli comparatively 

 stout, erect, repeatedly ramified, the branching somewhat secundly subdichot- 

 omous or occasionally subtrichotomous. Chromatophore in the younger cells an 

 irregular subspiral band, in the older apparently consisting of numerous minute, 

 more or less confluent granules. Sporangia on ramelli of the dorsal ramuli, 

 usually tetrahedrally divided (tripartite). Other parts unknown. 



9 



1. Grallatoria reptans M. A. Howe, sp. nov. 



Repent primary filaments simple or sparingly dichotomous, sinuous, 38-66 /j. 

 in diameter, their cells 1.5-2 times as long as broad, often bulging slightly above 

 the septum, their walls 5-13 ,u. thick; opposite lateral ramuli from nearly every 

 segment of the primary filament, the ascending prong simple, 200400 \i (48 

 cells) long, tapering, about 20 /* in diameter near base, about 8 /a at apex, the 

 deflexed stilt-like prong simple or once furcate, mostly 150-450 /i (46 cells) 

 long, slightly tapering, 20-26 /x in diameter; dorsal erect ramuli 1-4 mm. high, 

 springing usually from every second segment of the primary filament, their main 

 axes 3446 fi in diameter near base, the basal cell 1.5-2 times as long as broad, 

 the succeeding cells mostly 3-6 times as long as broad, the penicillate, or dimidio- 

 subfastigiate terminal divisions subsecund along the inner (anterior) faces of 

 the divisions; tetrasporangia obovoid or pyriform, solitary, or in twos or rarely 

 threes, 52-64 X 40-50 n (including wall, which is 6-S n thick), tripartite or 

 sometimes irregularly divided, mostly on one-celled pedicels; ovoid, globose or 

 pyriform densely granular cysts 60-150 n in diameter occasional, especially 

 near the distal ends of the deflexed gralliform filaments; color of plants 

 vinaceous-purple to dark vinaceous-brown (near the color of Wrangelia Argus). 



Forming a soft purple or reddish-brown lubricous velutinous coating in crevices 

 of surf-beaten rocks near the low-water mark, covering small shells, crustaceous or 

 prostrate algae, etc. In size and habit, the plant bears some superficial resemblance 

 to species of Acrochaetium or to Rhodochorton Rothii, but its affinities are apparently 

 with Wrangelia, from which, however, it amply differs in the characters indicated. 



Great Ragged Island (Howe 578$ type and 5766). 



3. GELIDIUM Lamour. Essai, 40. 1813. 



1. Gelidium rigidum (Vahl) Grev. Alg. Brit. lvii. 1830. 



Fucus rigidus Vahl, Nat. Selsk. Skr. 5 2 : 46. 1802. 

 Ahnfeltia (?) pinnatula Harv. Ner. Bor.-Am. 2: 169. 1853. 

 Echinocaulon rigidum Kiitz. Tab. Phyc. 18: 14. pi. 40. f. a-d. 1868. 

 Gelidiopsis rigidaWeb.-v. Bosse, Rec. Trav. Bot. Neer. 1: 104. 1904. 



Not uncommon in tide-pools and in shallow water, North Cat Cay, South Cat Cay, 

 Watling's Island, Mariguana, Caicos Islands, Great Ragged Island, and Salt Cay 

 Bank : Bermuda ; Florida ; and the West Indies in general. Type from St. Croix. 



