DICTYOTACEAE. 596 



2. PADINA Adans. Earn. PI. 2: 13. 17G3. 



Thallus consisting of only two layers of cells except near base ; tetrasporic sori just 

 above every second piliferous line and provided with evan- 

 escent indusium. 1, P. Sanctae-Cnicis. 



Thallus consisting of 3-6 layers of cells except at sometimes 

 bistratose apical margin ; tetrasporic sori scattered irreg- 

 ularly or forming an irregular confluent line near middle of 

 each interpilar zone, indusium subpersistent. 2. P. Tickcrsiac. 



1. Padina Sanctae-Crucis Borg. Dansk Bot. Ark. 2': 45. /. S7, 28. 1914. 



Common on rocks near the low-water mark. New Providence, Berry Islands, 

 Gun Cay, Exuma Chain, Crooked Island, Watling's Island, Mariguana, Caicos Islands. 

 Great Ragged Island. Orange Cay. and Anguilla Isles : — Bermuda and Florida to 

 northern South America. Type from St. Croix. 



2. Padina Vickersiae Hoyt, sp. nov.* 



Spatoglossum variegatum Kiitz. Sp. Alg. 560 p.p. 1849. 



Zonaria variegata Kiitz. Tab. Phyc. 9: 30 p.p. pL 73. f. II. 1859. Not 



Zonaria variegata. Lamour. Nouv. Bull. Sci. Soc. Philom. 1: 331. 1809. 

 Padina variegata Hauck, Hedwigia 26: 42. 1887; Vickers, Phyc. Barb. 2: 



37. pi. 8. 1908. Not Padina variegata Gaill. in Diet. Sci. Nat. 53: 



371. 1828. 



Thallus stipitate, 4—22 cm. tall, 5-37 cm. broad, entire when young, becom- 

 ing repeatedly more or less deeply laciniate, the segments var^'ing from cuneate- 

 spatulate to fan-shaped, sometimes encrusted with lime, the interpilar zones 

 1.5-8 mm. wide, often inconspicuous in older parts, the subterete, rhizoid- 

 covered stipe commonly 3—12 mm. long; lamina of 2 or 3 layers of cells at 

 revolute apical margin, of 4 layers throughout most of thallus, becoming 6-8 

 layers toward base; epidermal cells about one half as long as the central cells; 

 dioicous; antheridia and oogonia in often broken lines near the middle of each 

 interpilar zone, occurring on both surfaces but chiefly on the ventral, the 

 oogonia with a thin evanescent indusium, the antheridia naked; tetrasporangia 

 borne in a similar manner, often in scattered irregular sori near middle of 

 interpilar zone, the thin indusium commonly subpersistent. 



Type a tetrasporic plant collected from Fort Macon .iettv, Beaufort. North 

 Carolina, by W. D. Hoyt. August 23, 1907, and deposited in the V. S. National 

 Herbarium. Representatives of this species have often been erroneously identified with 

 Pnrlina vavouia (L.) Gaill. and /'. DurrUlaci Bory. Pndinn diibia Hauck. from East 

 Africa, is a much closer relative and may prove to be identical. 



In shallow water. New Providence, Berry Islands, and Eleuthera : — Bermuda 

 and North Carolina to Brazil. Type from North Carolina. 



3. NEUROCARPUS Web. & Mohr, Beitr. Naturk. 1: 300 (242-246). 1805. 



DiCTYOPTERis Lamour. Nouv. Bull. Sci. Soc. Philom. 1: 332. 'My 1809. 

 PoLYPODOiDEA Stackh. Mem. Soc. Imp. Nat. Moscou 2: 96, 97. 1809. 

 Haliseris (Mich.) Ag. Sp. Alg. 1: 141. 1820. 

 1. Neurocarpus Justii (Lamour.) Kuntze, Eev. Gen. PI. 2: 907. 1*^91. 



Dictyopteris Justii Lamour. Nouv. Bull. Sci. Soc. Philom. 1: 332. pJ. 6. 



f. 2 A. 1809. 

 Haliseris Justii Ag. Sp. Alg. 1: 142. 1820. 



On rocks in 1-20 meters of water. Gun Cay. Abaco, and Green Turtle Cay : — 

 Bermuda and Florida to Barbados. Type from Santo Domingo. 



Neurocarpus (lelicatulus (Lamour.) Kuntze is of general occurrence In the West 

 Indian region and is to be expected in the Bahamas. It is a much smaller and more 

 delicate plant than N. Jvatii, the thalhis segments being mostly only 1-4 mm. 

 broad, while in N. Justii they are 1-3 cm. broad; when living it commonly shows 

 beautifully iridescent blue-green hues. It grows in sheltered and well-shaded places. 



* This preliminary diagnosis is published with the permission of the U. S. Com- 

 missioner of Fisheries. 



