DICTYOTACEAE. 509 



reaching a height of five or six inches, is rather more lobeii, the fan-shape<l 

 lobes mostly 1^-3 inches broad, and is less whitened by lime on its ventral 

 surface. Sections show that the thallus is 3-6 cells thick except for a narrow 

 zone at the apical margin, where it is but 2 cells thick. The tetrasporic sori 

 are mostly in the form of compact dot-like clusters scattered irregularly in each 

 interpilar zone or forming a narrow irregular line a little above the middle of 

 the zone; indusium subpersistent. (Phyc. Bor.-Am. 2083, as Padina variegata.) 



Neurocarpus delicatulus (Lamour.) Kuntze [Dictyopteris deUcatula 

 Lamour. ; Haliseris delicotula (Lamour.) Ag.] occurs on rocks in shallow 

 water in well-shaded and sheltered places, as at Red Bay, St. David 's Island. 

 The species of this genus are distinguished from other members- of the family 

 by possessing a thallus with a distinct midrib. In the present species the 

 thallus is of thin delicate texture and is several times regularly and somewhat 

 divaricately forked. It reaches a length of 2 or 3 inches and the thallus seg- 

 ments are i to 2 lines broad. Dried specimens are a brownish or yellowish 

 olive-green, but when living and immersed it often shows brilliant iridescent 

 blue-green hues. The species was first described from Santo Domingo and i"? 

 typically West Indian in its distribution. (Phyc. Bor.-Am. 19S4, as Dictiiop- 

 teris deUcatula.) 



Neurocarpus Justii (Lamour.) Kuntze [Dictyopteris Jiistii Lamour.; 

 Haliseris Justii (Lamour.) Ag.] is a much larger plant that grows on rocks in 

 more exposed places, mostly in 1^20 feet of water. The thallus is collate and 

 several times dichotomous, as in the last, but it reaches a length of 8-12 inches 

 and its segments are i-li inches broad. Its color is a dark olive or a fuscous 

 brown. It is often found washed up on the South "Shore. Like the last, it was 

 first made known from Santo Domingo and is a typically West Indian species, 

 (Phyc. Bor.-Am. 19S5, as Dictyopteris Justii.) 



Dictyota Bartayresii Lamour. (Dictyota crispata Lamour. ; Dictyota par- 

 dalis Kiitz.) occurs in shallow water, as at Spanish Point, in the ponds of 

 Walsingham, and at St. David's Island. It forms loosely intertangled mats 

 3-6 inches high. The thallus ig repeatedly dichotomous and its segments are 

 mostly 1-3 lines broad, with margins entire or irregularly proliferous. The 

 species of Dictyota are difficult to define. The form of the thallus, width of 

 the segments, etc. evidently vary greatly according to conditions of growth, and 

 it is probable that more species are currently recognized than may be reasonably 

 assumed to exist in nature. (Phyc. Bor.-Am. 1874.) 



Dictyota dichotoma (Iluds.) Lamour. is less common in Bermuda than the 

 preceding species. It is more regularly and less divaricately dichotomous an<l 

 has a broader thallus, with segments mostly '2-4 lines wide. (Phyc. Bor.-Am. 

 2175.) 



Dictyota ciliolata Kiitz. (Dictyota ciliata J. Ag.— not D.ciliota Lamour.; 

 Dictyota crenulata Collins in Phyc. Bor.-Am. 1875— not D. crcnulata J. Ag.) 

 occurs in Harrington Sound, in pools on the South Shore, etc. The thallus 

 has few or many small simple teeth or short cilia on its margins; its segments 



