NO. 1 DAWSON : MARINE RED ALGAE OF PACIFIC MEXICO 117 



Jania decussato-dlchotoma (Yendo) Yendo 

 Plate 27, fig. 3 



Yendo, 1905, p. 37. Corallina decussato-dichotoma Yendo, 1902a, p. 

 25, pi. 3, figs. 1-3, pi. 7, figs. 3-4. Jania rubens (L.) Lamx., as inter- 

 preted by Dawson, 1944, p. 227 in part. 



Thalli saxicolous or apparently so, forming alone, or with other 

 small, low algae, sponges, debris, etc., a dense turf several cm. in extent 

 and 1 cm. or more thick; branching irregularly decussate-dichotomous, 

 the angles mostly wide; branches cylindrical throughout, (100) 120-170 

 (180) II in diameter, 2.5-5.0 diameters long; apices blunt; tetraspor- 

 angial conceptacles infrequent, 210-300 ju, in diameter, urn-shaped, more 

 or less rostrate, terminal and antenniferous or non-antenniferous. 



Type: None designated. 



Type locality: Japan. No specific locality indicated (Misaki: 

 Prov. of Boshu; Prov. of Hiuga). 



Mexican distribution: Gulf of Calif. — Common at all seasons 

 in the southern part of the Gulf: Vicinity of Guaymas, Bahia Concep- 

 cion, Puerto Escondido, Isla Carmen, Bahia Agua Verde, Bahia de La 

 Paz, Punta Frailes. Pacific Baja Calif. — Not yet detected although two 

 collections from La Jolla, California seem to be in good agreement both 

 with the Gulf collections and with Yendo's description of the species 

 in Japan. 



As Yendo pointed out, the original description of Jania adhaerens' 

 Lamx. applies equally well to Jania decussato-dichotoma and to several 

 other species. Accordingly, the latter and various other species have been 

 identified with the confusing and actually unknovv^n /. adhaerens. The 

 rejection of the name /. adhaerens Lamx. from current and future liter- 

 ature seems long overdue, for in the absence of (1) an adequate de- 

 scription, (2) of a type specimen, (3) of an authentic illustration, and 

 (4) of the source of the original material, no suitable interpretation of 

 the name is possible. As Taylor has shown (1945, p. 196), the applica- 

 tion of the name has differed widely even among the most competent 

 authors. 



Several varied specimens, including some of the present species, were 

 lumped tentatively under Jania rubens (L.) Lamx. in the earlier account 

 of the Gulf of California algae (Dawson, 1944) to await more ample 

 collections. It now^ appears that none of our plants satisfactorily agree 

 with the European /, rubens, which, to judge from several imperfect but 

 relatively recent accounts of the species (Rosenvinge, 1917; Manza, 

 1940; Newton, 1931; Taylor, 1928) is understood as a moderately 

 large plant, 2-5 cm. high, 150-250 ju, in diameter below, and 100-160 /a 

 in diameter above, with segments 3-6 diameters long. 



