HowWE: PHYCOLOGICAL STUDIES 493 
obovoid, the longer axis being nearly always in the longitudinal or 
vertical plane rather than in the transverse. As in Hawaiian 
specimens, the utricles of the subcortial layer are smaller and 
less bullate than in the plants of southern Florida and the West 
Indies, but they have a maximum diameter of 68-175u and are 
always much larger than the peripheral utricles; they also form a 
compact flat-topped stratum, very different from anything that 
occurs in H. Tuna. The firmly coherent, often interlocked and 
fusing peripheral utricles, and the light calcification, together with 
the characters previously mentioned, leave no doubt as to the 
correctness of identifying the plants with H. discoidea. 
The finding of a Halimeda on the coast of Lower California is 
of particular interest in extending our knowledge of the distribution 
of this genus. So far as is known to the writer, the only previous 
record of the occurrence of a Halimeda on the Pacific coast of 
the American continents is that given by Miss Ethel Sarel Barton 
[Mrs. Gepp] in her monograph of ‘‘The Genus Halimeda,”’ where, 
under the stations for Halimeda Tuna, is given “‘Payta, Peru, 
Sinclatr.”’ 
CopIuM TOMENTOSUM (Huds.) Stackh. Ner. Brit. xxiv. 1797 
Fucus tomentosus Huds. Fl. Angl. 584. 1778. 
La Paz, Vives 8 and r4. 
The specimens from Baja California communicated under the 
above numbers are a little more rigid than is usual in Codium 
tomentosum, and the walls of the peripheral utricles are for the 
most part conspicuously thickened at their apices, being there 
commonly 8-27y thick, though occasionally only 3-4u. We find 
no trace of a mucro even in the younger parts and can discover 
no sufficient ground for considering the plants distinct from C. 
tomentosum, with which they agree well in size and habit. The 
thickened apices of the utricles are slightly suggestive of those of 
the Australian Codium galeatum J. Ag., but they are not con- 
tracted-umbonate as in that species and the plants have not the 
size and habit of that species. Certain Jamaican specimens which 
we have referred to C. tomentosum, sometimes have the apical 
walls of the peripheral utricles even more thickened than in these 
plants from Lower California, and European specimens occasion- 
