88 COLLINS AND HERVEY. 



DICTYOPTERIS Lamouroux. 



1. Frond thick, wide, Fucus-like. 2. D. Justii. 



1. Frond thin, delicate. 2. 



2. Diagonal veins from midrib to margin. 3. D. plagiograrnma. 



2. No lateral veins. 1. D. delicatula. 



1. D. DELICATULA Lamouroux, 1809, p. 332, PL VI, fig. 2 B; 

 Vickers, 1905, p. 58; 1908, part 2, PL III; Borgesen, 1914, p. 216, 

 fig. 166; P. B.-A., No. 1924. Castle Harbor, Jan., Farlow; Cave, 

 Gravelly Bay, Oct., Harris Bay, Heron Bay, Dec., Hervey. Not 

 uncommon, but mostly small plants, not over 10 cm. high. 



2. D. JUSTII Lamouroux, 1809, p. 330, PL VI, fig. 2 A; Vickers, 

 1905, p. 58; 1908, part 2, PL V; P. B.-A., No. 1925. Rein, as Haly- 

 seris polypodioides; Mosely, dredged in 31 fathoms; Wadsworth, 

 March, No. 9; St. David's Island, April, Kemp, as Fucus ceranoides; 

 Faxon; Gravelly Bay, Jan., Feb., Oct., Dec., Hervey; Gravelly Bay, 

 April, July, Aug., Tucker's Town, April, Outer Reef, Ely's Harbor, 

 Hungry Bay, July, Cooper's Island, Aug., Collins. Occasionally 

 found growing just below low water mark, but mostly floating, coming 

 from deeper water. Old and battered plants came in abundantly in 

 August; only young plants were found in February. It may grow to 

 a length of 40 cm. Most reports of species of Fucus from Florida and 

 the West Indies are based on large specimens of this species. Tetra- 

 spores were found in abundance on plants collected in August; they 

 occur on both sides of the frond, the sori originally circular, about 

 1 mm. diam., or elongate, about 1 mm. wide. They increase in size, 

 often become confluent, forming irregular patches, more than 1 cm. 

 across. The sporangia are broadly pyriform, about 45 /* high, 25- 

 35 ,u diam. seen from above, and closely packed. 



3. D. PLAGIOGRAMMA (Mont.) Vickers, 1905, p. 58; 1908, part 2, 

 PL IV; Haliseris plagiogramma Montagne, 1837, p. 356. Kemp, 

 May, as Haliseris polypodioides; this single specimen, large and in 

 fine condition, is the only Bermuda record. 



DICTYOTA Lamouroux. 



1. Margin with small sharp teeth. 3. D. ciliata. 



1. Margin even or uneven, without teeth. 2. 



2. Frond rather broad, with more or less distinct rachis, bearing alternate 

 divisions; tips not tapering, either blunt or with two points. 



8. D. dentata. 



