GEAl^ ZU SOLMS-LATJBACH — MONOGRAPH OF THE ACETABULAlMEiE. 25 



Compare what has been said on this point under ^. den fata. Should these dillerenccs 

 prove constant on farther investigation, they Avould yiekl important dillerential characters, 

 but this cannot be established on the scanty material of our collections. 



Typical specimens of A. crenulata are very easily recognized even at the first glance. 

 All the same, there are forms which connect with the following species so well that 

 their determination becomes difficult. The precise limits of the species must l}e laid 

 down after farther study on richer material. 



7. AcETABULAiiiA CARAiBicA, Ktitz. Tab. Phyc. vi. 1851), t. 93. 



Disc mostly flat, slightly calcified, often almost without lime, terminah Rays fairly 

 numerous, 34i-40, in the larger forms 50-GO, firmly united ; apex depressed in the middle,, 

 somewhat sunk, with a small apiculum, sometimes not distinct. Corona superior and 

 inferior as in^. crenulata, the former with two hair-scars, one behind tlie otlier, on each 

 segment. 



Size : diam. of disc 6 mm. ; breadth of corona superior 015 mm. ; spore diam. 0*1 mm. 

 (Plate I. tig. 10.) 



Mab. Guadeloupe : coll. Duchassaing (Hb.Gotting. Berl.) ; Maze & Schramm, no. 1317 

 (Pointe-a-Pitre) ; Herb. Tliuret, Berl. Strasb. This number is a form approaching 

 A. crenulata ; Moule, " sur des pierres detachees au fond du port," 27(3, Hb. Thuret. 



As already stated in the description of A. crenulata, this species is very nearly related 

 to it, but is generally to be distinguished by the terminal, flat, and slightly calcified cap, 

 and the unusual form of the points of the rays. Especially if it bear several caps above 

 each other {^A. caraihica, )3 cali/culata, Kiitz.) it is to be regarded with caution. As a 

 matter of fact, one often finds in herbaria, under the latter name, typical specimens of 

 A. crenulata. On the other hand, it may resemble the following form very much if the 

 apiculum disappears ; indeed Agardh has united them, as appears from his diagnosis ; how- 

 ever, they are to be distinguished by the number and position of the coronal segments. 



y8. Sporangial rays blunt, more or less scolloped at the margin, apiculum absent. 



I. Segments of the corona superior with about four hair-insertions ; rays united by the 

 calcification of the side-walls, but completely separate after treatment with acid. 



8. AcETABULAKiA Stjhrii, n. sp. Gracilis, disco subinfundibulifornii. Disci radii 



obtusi vel cmarginato-prsemorsi. Processus coronas superioris pilis quaternis uni- 



radiatis obssesi. Syn. A. caraibica, Ag. ex parte. 

 Belongs to the smaller forms (total height li-3 cm.). Stalk stiff, strongly calcified, 

 bearing a single, terminal, infundibuliform disc, slightly calcified, and that principally 

 in the side-walls. Sporangial rays in moderate number (25-30), with blunt margin, 

 as if bitten off and more or less deeply scolloped. Segments of the corona inferior of 

 somewhat rectangular outline, externally slightly emarginate, those of the corona superior 

 separated from each other by distinct interspaces, irregularly elongate, externally as a 

 rule somewhat deeply scolloped, with 3-1 (mostly 1) hair-scars, of which the outermost 

 may be thrust aside. 



Size: diam. of cap G-7 mm.; breadth of corona superior O'OO mm. (Plate I. figs. 9, 13.) 



SECOND SERIES. — BOTANY, VOL. V. ^ 



