546 University of California Puhlications in Botany [Vol. 8 



pseudoparenchymatous axis (cf. also Harvey, Phyc. Brit., pi. 82, 

 1847). Agardh also emphasizes in his generic diagnosis the formation 

 of gametangia as projecting ramelli arising from the upper cells of 

 the cortical filaments. The illustrations of Thuret (1850, pi. 27) show 

 exactly the type of cortical filaments and gametangial formation upon 

 which, as distinctive characters, Derbes and Solier founded their 

 genus. So far as we are able to discover, the three genera, Castagnea, 

 Cladosiphon, and Eudesme are to be united and, since Cladosiphon is 

 the earliest name, unless we adopt JEgira Fries of doubtful status, we 

 might feel compelled to use Cladosiplion as the name of the genus to 

 which we may assign species usually referred to Castagnea or to 

 Eudesme. Cladosiplion, as we understand Kuetzing's type species, 

 CI. niediterraneiis {Mesogloia fistidosa Menegh., Castagnea fistidosa 

 (Menegh.) Derb. and Sol., C. polycarpa Derb. and Sol. and Castagnea 

 mediterramea (Kuetz.) Bornet) is however, usually understood in the 

 sense of J. G. Agardh (1882, pp. 40 and 42). J. G. Agardh, on the 

 other hand, based his idea of Cladosiphon on Liehniannia Posidoniae 

 Meneghini (1843, pp. 300-304, pi. 5, fig. 1) which has its gametangia 

 situated very differently from those of the members of the Clado- 

 siphonr-Castagnea-Eiidesme complex. Meneghini 's species seems to 

 have the gametangia arising as transformed branches of the cortical 

 filaments and slender, with uniseriate loculi, not pronouncedly sili- 

 quaeform as in Liehniannia and not arising unilaterally from the 

 upper cells of the cortical filaments as in the complex we are discussing. 

 We have one species, from the Gulf of California, seemingly cogeneric 

 with Meneghini 's Liehniannia Posidoniae for which we have proposed 

 the generic name Meneghiniella (Phyc. Cont. VII, 1924, p. 5). 



It remains to consider the oldest name possible for this Cladosiphon- 

 Castagnea-Eiidesme complex and that is ^gira Fries (1825, p. 342). 

 Fries founded his genus on the Linckia Zosterae Lyngbye (1819, 

 p. 194, pi. 66, fig. C) which may or may not be the Rividaria Zosterae 

 Weber and Mohr (1810, p. 367). The plant of Lyngbye has been 

 variously interpreted by J. G. Agardh (1848, p. 53) and Areschoug, 

 who had an authentic specimen for comparison (Areschoug, Alg. 

 Scand. Exsicc, ser. 1, no. 67, and 1842, pp. 228-230). The evidence 

 is well discussed by Kylin (1907, pp. 85-87). While there may be 

 reasonable doubt as to whether Lyngbye 's plant is the same as Eudesme 

 virescens (Carm.) J. Agardh, or Eudesme Zosterae (J. Ag.) Kylin, 

 it is to be placed in the Cladosiphon-Castagnea-Eudesme complex 

 which ought, therefore, to take the name jEgira (cf. also, M. A. Howe, 

 1918, p. 505). 



