ANTITHAMNION 151 
present. Хо. 38 is antheridial. The antheridia are soon соп- 
fluent along the ventral (upper) faces of the ramuli; they are some- 
what similar in general character to those figured by Thuret 
(Etudes Phyc. pl. 33) for Callithamnion corymbosum, but are 
finally confluent for several consecutive segments and the lateral 
cells from which the antheridial cluster is evolved are larger, both 
relatively and absolutely, than the corresponding cells in C. 
corymbosum. No. 57 bears sporangia and polyspores; the spo- 
rangia are sessile, ellipsoid, obovoid or finally subglobose, and 
55-70 и in greatest diameter. So far as we are aware, the spo- 
rangia have not before been observed on Peruvian plants. De- 
Toni’s reference of the species to the genus Pleonosporium appears 
to have been due to J. Agardh’s hint that P. vancouverianum J. Ag., 
the sporangia of which were known, might be the same as the 
Peruvian plant. Setchell and Gardner (Univ. Calif. Publ. Вог. т: 
338. 1903), as well as J. Agardh, have been impressed by the 
resemblance of P. vancouverianum to Kiizting’s figure of the 
earlier-published Callithamnion venustissimum. We have seen 
no specimens of the British Columbian and Washington plant, 
and are therefore in no position to hold an opinion as to the 
synonymy alleged by De-Toni to subsist. 
CALLITHAMNION MYURUM Suhr (Flora 23: 282. 1840; Kiitz. 
Tab. Phyc. 11: pl. 88. f. d-f. 1861) was described as coming from 
"Lima" (Callao?) and as occurring on ‘‘Sphaerococcus corneus 
Ag." which is apparently the plant to which J. Agardh soon 
afterwards gave the name Gelidium seminudum. Nothing like it 
has been detected among Dr. Coker's specimens. 
ANTITHAMNION Naeg. Neu. Algensyst. 200. 1847 
Antithamnion densum (Suhr) comb. nov. 
Callithamnion densum Suhr, Flora 23: 281. 1840. 
Callithamnion floccosum Mont. Fl. Boliv. 11. 1839. Not C. 
Лоссозит Ag. Sp. Alg. 2: 158. 1828. 
Plant small, delicate, fragile, 1-2.5 cm. long, repent in the 
lower parts and there more or less involved in mucus; main axis 
commonly denuded below, 95-140 и broad, 3-8 times subdichot- 
omous by the strong developmen: of one of a pair of opposite 
