COEALLINACEAE. 587 



4. Lithophylluin munitum Fosl. & Howe, Bull. N. Y. Bot. Gard. 4: 132. pi. 86, 

 88, 89. 1906. 



CoTering an old coral near low-water mark under shelving rocks, Cave Cays, 

 Exuma Chain : — Jamaica and Porto Eico. Type from Cave Cays. 



5. POROLITHON Fosl. K. Norske Vidensk. Selsk. Skr. 

 1909^: 57. 1909. 



Vertical sections (of decalcified material) showing vertical rows of small oval, sub- 

 globose, or ellipsoidal perithallic cells, mostly 4— 12« high, with the firmly coherent 

 horizontal lamellations usually obscure or unrecognizable ; 

 grouped heterocysts mostly 13-15 » broad. 1. P. pachydermum. 



Vertical sections (of decalcified material) showing distinct 

 horizontal lamellations, easily separable in pairs, each pair 

 consisting of one moderately long-celled layer (cells 12-25 » 

 high) and one inconspicuous short-celled layer (cells S-Su, 

 high) ; grouped heterocysts mostly 20— 26u brpad. 2. P.improcerum. 



1. Porolithon pachydermum (Fosl.) Fosl. loc. citr 



Lithopiiyllum oncodes pachydermum Fosl. Ice. cit. 1904': 5. 1904. 

 Lithophyllum pachydermum Fosl. K. Norske Vidensk. Selsk. Aarsber. 1905 : 

 22(6). 1906. 



On rocks, corals, corallines, etc., near low-water mark. New Providence, Berry 

 Islands, Great Bahama, South Cat Cay, Atwood Cay, Mariguana, and Great Bagged 

 Island : — Jamaica ; Porto Eico ; American Virgin Islands ; and Barbados. Type from 

 West Indies. 



2. Porolithon improc^rum (Fosl. & Howe) Lemoine; in Borg. Dansk Bot. Ark. 



3': 151. 1917. 



GonioUthon improoerum Fosl. & Howe, K. jSTorske Vidensk. Selsk. Skr. 



1907«: 24. 1907. 

 HydrolUhon improcerum Fosl. loc. cit. 1909^ r 55. 1909. 



On old corals or calcareous rocks, near low-water mark. 



The basis for recording this species from the Bahamas is a note from M. Foslie 

 (i» Utt.) to the effect that a specimen of GonioUthon propinquum (= ff. soluMle) 

 from Mariguana (Howe 5SS6) was " partly covering OonioUthon (BydroUthon) impro- 

 oerum." In the type (from Jamaica), the species accompanied Porolithon pachy- 

 dermum, which it resembles in habit. In structure the plant is suggestive of Litho- 

 phyllum prototypum, from which, however, it differs in the presence of heterocysts 

 (in groups) as well as in general habit and in the mostly smaller conceptacles. 



6. FOSLIELLA M. A. Howe, nom. nov. 



Type: Melobesia farinosa Lamour. Hist. Polyp. 315. pi. IS. f. 3. 1816. 

 MELOBESlAjSubgen.EuMBLOBBSlA Fosl. K.Norske Vidensk. Selsk. Skr. 1905^: 1905. 

 Melobesia Lamour. p. p. min. Hist. Polyp. 313. 1816. Not Melobesia Lamour. 



Nouv. Bull. Sci. Soc. Philom. 3: 186. 1812 (type, CoralUna memiranacea 



Esper). 



Thallus 1-3 cells thick. 



Heterocysts present ; growing on other algae. 1. F. farinosa. 



Heterocysts wanting ; growing on Thalassia. 2. F. LejolisU. 



Thallus mostly 8-10 cells thick except at or near the unlstra- 



tose margin ; growing on Ghamaedoris. 3. F. Ohamaedoris. 



1. Fosliella farindsa (Lamour.) M. A. Howe, comb. nov. 



Melobesia farinosa Lamour. Hist. Polyp. 315. pi. IS. f. S. 1816. 



On various algae (Dictyota, Dilophus, Padina, Sargasstim, and Polysiphonia), 

 in shallow water, very common, Eose Island, Berry Islands, Watling's Island, Mari- 

 guana, and Little Inagua : — Massachusetts to Barbados ; widely distributed. Type 

 European. 



