294 PAPERS FROM THE DEPARTMENT OF MARINE BIOLOGY. 



is justifiable, the first Goniolithon Foslie becomes, under the "American Code" 

 of nomenclature, a synonym of Lithophyllum, while the second Goniolithon, 

 being a homonym of the first, is invalid, though under the "Vienna Rules" 

 of nomenclature such a change in the application of the generic name might 

 be tolerated. However, the definition of genera among the Lithothamnieae 

 is at present on such an uncertain basis and so many questions of generic 

 priority and typification in this group remain to be solved that the writer 

 is not now disposed to disturb current usage by trying to suppress the name 

 Goniolithon. The species recognized under this generic name by Foslie in 

 1900 and afterwards, and later by De-Toni 1 and by Svedlius, 2 seem to form a 

 very natural group, which may well deserve generic recognition. Mme. 

 Lemoine, in her recent 3 attempt to emphasize the importance of vegetative 

 characters in defining genera in this family, has reduced Goniolithon, even in 

 its second application, to a synonym of Lithophyllum. But, even in their 

 vegetative anatomical characters, the species of Goniolithon in its secondary 

 sense, so far as they are known to the writer, offer certain points of difference 

 from the typical species of Lithophyllum in its current application. The 

 cells, especially the perithallic, are less distinctly and regularly stratified than 

 those of species of Lithophyllum, this difference being due in part but not 

 wholly to the usual occurrence in the perithallia of larger, firmer-walled, for 

 the most part irregularly disposed cells known as "heterocysts." And the 

 cell-walls, particularly those of the hypothallic cells, appear to be firmer and 

 more rigid than those of species of Lithophyllum; at least, when decalcified 

 and stained with hematoxylin, they seem to have a peculiar texture and color 

 that, once grasped, is easier to recognize than to describe. However, as has 

 been emphasized by Svedelius (loc. cit., p. 275), it was upon the characters of 

 the tetrasporic and cystocarpic conceptacles that Foslie based his second 

 Goniolithon, and, as is now generally recognized by phycologists, it is on such 

 characters that genera are most naturally and firmly grounded. Just how 

 constantly the species currently grouped under Goniolithon may differ from 

 those currently grouped under Lithophyllum in the character of their concep- 

 tacles is to be determined by future investigations. 



Goniolithon fosliei (Heydrich) Foslie. 



Goniolithon fosliei (Heyd.) Fosl., in Gardiner, Faun, and Geog. Maldive and Laccadive Arch., vol. I, p. 470, 

 plate 25, fig. 3, 1903; Siboga-Exped. Monog. 6i, p. 46, fig. 19 + plate 9, fig. 1-5, 1904. 



Lithothamnion fosliei Heyd., Ber. deutsch. bot. Ges., Bd. 15, p. 58, fig. 1 + plate 3, figs. 9-11, 1897. 



Lithophyllum Josliei Heyd., Ber. deutsch. bot. Ges., Bd. 15, p. 410, 1897; Lemoine, Ann. Inst. Oceanog., 

 t. 2, fase. 2, p. 142, fig. 71, 191 1. 



Forming a closely adherent crust on old corals, "1,400 feet from shore, line I, south- 

 east reef." The crusts are 0.5 to 1 mm. thick; the hypothallium is well developed and 

 "coaxial," its cells mostly 24 to 38 /x by 12 to 22 n; the cells of the perithallium exceedingly 

 variable in size, 9 to 25 ju in maximum diameter, mostly subquadrate in section, but often 

 twice as broad as high or vice versa; heterocysts numerous and occasionally in vertical rows 

 as described for G. fosliei by Heydrich and by Foslie; the few conceptacles 0.6 to 1 mm. broad, 

 measured from above. 



'Syll. Alg., vol. 4, pp. 1797-1804, 1905. 



l In Engler und Prantl, Nat. Pflanzenfam., Theil I, Abth. 2, Nachtrage, pp. 269, 275, 1911. 



•Ann. Inst. Oceanog., t. 2, fasc. 2, p. 64, 1911. 



