45 8 BULLETIN OF THE BUREAU OF FISHERIES. 



distribution of the son is the same as that of P . richer sice, but it is certainly closely similar ( " P. variegata ' ' 

 and P. dubia being placed in the same group by Hauck on the basis of this character), and in other 

 respects the two species seem identical. It seems, therefore, very probable that these belong to a single 

 species. But, in view'of some uncertainty regarding similarity in the arrangement of the son and in 

 view of the opinion expressed by Hauck that his material of P. dubia did not entirely agree with the 

 "Zonaria variegata" of Kuetzing, it has seemed better to keep the species separate until P. dubia can 

 be more thoroughly studied . If the two are found to belong to a single species, both P . variegata ( Kuetz . ) 

 Vickers and the present name must be reduced to synonyms. 



The type of the species here described is a tetrasporic plant from Fort Macon jetty, Beaufort, N. C., 

 August 23, 1907. This and several cotypes have been deposited in the U. S. National Herbarium. 



The tetrasporangia, oogonia, and antheridia aretx>rne on separate plants (the species being dioecious), 

 and the sexual and asexual generations seem, from the results of Wolfe (1913, 1918), to alternate with 

 each other as in Dictyota. There is evidence (Wolfe, 1918), for believing that the eggs may be fertilized 

 before being discharged from the oogonium. Unfertilized eggs may commence their development 

 parthenogenetically as in Dictyota, but apparently never (Wolfe, 1914, 1918), under such conditions, 

 reach maturity . x According to observations of Howe, the tetrasporangia also may commence develop- 

 ment without undergoing division, forming many-celled brood buds or propagula. The further history 

 of these bodies is unknown. 



The portions of the cuticle covering the sori are raised by the developing tetrasporangia and oogonia 

 as distinct indusia covering the fruiting areas (PI. CXIV, figs. 1-3), while those covering the antheridia 

 are not raised as distinct layers, and the antheridia accordingly appear naked. Although Borgesen 

 (1914) figures an indusium covering the antheridial sorus, the author, after careful study of sections 

 of well-preserved material, has been unable to find these in any case. In spite of this discrepancy, 

 the plants of Borgesen and those referred to here almost certainly belong to the same species. The 

 indusia, when present, are very delicate and are finally ruptured by the developing sori; they are, 

 consequently, often absent from mature fruits and frequently are not evident on dried plants. The 

 tetrasporic and female plants closely resemble each other but can easily be distinguished by the fact 

 that the tetrasporangia have about twice the diameter of the oogonia, mature tetrasporangia measuring 

 41 to 90 by 47 to 108 mic. and the oogonia 27 to 45 by 36 to 63 mic. Frequently, moreover, all the 

 oogonia on a single plant are of the same age, while the tetrasporangia, although usually of the same 

 age in a single zone, are borne in successively younger zones toward the apical margins. There is some 

 evidence that the sexual cells are borne in periodic crops at weekly intervals, but in other cases oogonia 

 (or antheridia) of several different ages are borne on the same individual. 6 



Two other species of Padina are recorded from the West Indies. These, if found, 

 may be distinguished from the present species by the following characters : 



P. sanctae crucis Borgesen. Frond consisting of two cell layers, tetrasporangial sori in concentric 

 zones above each alternate line of hairs. 



P. gymnospora (Kuetzing) Vickers. Frond consisting of three cell layers, tetrasporangial sori in 

 concentric zones in middle of each alternate zone between the lines of hairs, sori not covered by indusia. 



Genus 3. Spatoglossum Kuetzing. 



Spatoglossum, Kuetzing, 1843, p. 339. 

 Spathoglossum, De Toni, 1895, p. 246. 



Frond flat, ribbonlike, subpalmate-dichotomous, growing by groups of cells at the 

 apices, surface uniform, zonations lacking; margin smooth or dentate; midrib lacking; 

 cortex composed of a single layer of cells arranged in straight parallel lines; inner stratum 

 composed of several layers of cells; spores produced four in a sporangium; sporangia 

 scattered over both surfaces, occurring singly or several together in small groups; 

 oogonia and antheridia produced on different plants; oogonia occurring singly, scattered 

 over the surface; antheridia in small, scattered, inconspicuous sori. 



About eight species, in warm and tropical seas. 



a The author is gratefully indebted to Dr. Marshall A. Howe for permission to refer to these unpublished results. 



'The author is indebted to Prof. J. J. Wolfe for considerable information regarding the life habits of Padina at Beaufort. 



