CORALLTXACEAE. 587 



4. Lithophyllum munitum Fosl. & Howe, Bull. N. Y. Bot. Gar.l. 4- }[V> pi SO 

 88, 89. 1906. ' 



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

 Exuma Chain : — Jamaica and I'orto liico. Type from Cave Cays. ' 



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

 1909=': 57. 1909. 



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

 globose, or ellipsoidal perithallic cells, mostly 4-12(1 high, with the firmly coherent 

 horizontal lamellations usually obscure or unrecognizable ; 

 grouped heterocysts mostly 13-15^ broad. 1. P. pachydennuin. 



Vertical sections (of decalcified material) showing distinct 

 horizontal lamellations, easily separable in pairs, each pair 

 consisting of one moderately long-celled layer (cells 12-2~>ix 

 high) and one inconspicuous short-celled layer (cells 3-Gu 

 high) ; grouped heterocysts mostly 20-26 u broad. 2. P. improccrum. 



1. Porolithon pachyderraum (Fosl.) Fosl. loc. cit. 



LithophyUum oncodes pachydermum Fosl. loc. 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 Ragged 

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

 West Indies. 



■)> 



2, Porolithon improcerum (Fosl. & Howe) Lemoine; in Borg. Dansk Bot. Ark. 



3^: 1.51. 1917. 



Goniolithon improcerum Fosl. & Howe, K. Norske Vidensk. Sclsk. Skr. 



1907«: 24. 1907. 

 Hydrolithon improcerum Fosl. loc. cit. 1909": 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 

 (in litt.) to the effect that a specimen of Goniolithon propinquum {— G. soluhilc) 

 from Mariguana (H oh- e 5330) was "partly covering Goniolithon (IlydroUthon) impro- 

 cerum." 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 prototypuni, 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. FOSLIEIiLA M. A. Howe, nom. nov. 



Type: Melohesia farinosa Lamour. Hist, Polyp. 315. pi. 12. f. 3. 1816. 

 MELOBESiA,subgen.EuMELOBESiA 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 membranacea 



Esper). 



Thallus 1-3 cells thick. 



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



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



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



tose margin ; growing on Cliamaedoris. 3. F. ChamacOoris. 



1. Fosliella farinosa (Lamour.) M. A. Howe, condx nov. 



Melobesia farinosa Lamour. Hist. Polyp. 315. pi. 1'2. f. S. 1816. 



On various algae (Dictyota, Dilophus. Pudina, Sargassuin, and Polysiphonia), 

 in shallow water, verv common. Rose Island, Berry Islands. Watling's Island, Marl- 

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

 European. 



