THE CODIUMS OF Till-; JUAN FERXANDKZ ISLANDS 589 



basibus paucis pluribusve, elongatis et ipsis dactyliformi convolutoque sinuosis, 

 verticaliter compressis et ipsos sinuoso arete complectentibus, thallum totum 

 cerebri formem efhcientibiis; utriculis mox dense ramosis, ramulis pyramidaliter 

 oriendis positisque, macrosteno-physis, usque ad 650 — 725 ;j. longis et ad 

 60 — 75 u- latis, apice fornicatis, nunc rotundis, nunc obtuse conicis, niembrana 

 apicali tenue usque ad 5 m, crassa, levi, sub af)icibus plus niinusve et curto 

 tumescentibus et piliferis, pilis in verticillis irregularibus singulis usque ad plu- 

 ribus positis; gametangiis nondum visis. 



Masaticrra: No. 2, beach drift, Jan. 1917; No. 5, Bahia del Padre, lower 

 littoral, Station 2 B, Jan. 25, 191 7; No. 9, Santa Clara Strait, in 20' — 25 meters 

 depth, on NuUipore bottom, Mar. 27, 1917. (Type specimen, No. 2, Herb. 

 Univ. Calif. No. 549414). 



x'ls may be seen from the figures (plate 34, figures i — 3), the habit, 

 while varying somewhat in the three specimens available for study, still is 

 cerebriform pulvinate through the radiating, sinuous, compressed lobes which 

 are closely ap[)rcssed together (especially before being handled), and the sinuous 

 curves fitting into one another to form the brain-like habit. The differences, 

 probabh' one of greater or less luxuriance in development, are chiefly in the 

 matter of convexity of the pulvinus. No. 2 being the more rounded, while 

 Nos. 5 and 9 are more depressed and flattened out. The last two approach 

 the hahit of C. diiiiorpJium (see SvEDELlUS, loc. cit.), but both from the figure 

 as well as from the description of Svedelius, the character of the »lobes;' seems 

 different, those of C. dimorphnm being shorter and more segregated from one 

 another. In other words, there seems to be a discontinuity of the lobes of 

 C. dinwrpJmm and a greater elongated sinuosity in C. cerebrifornie. The two 

 species are undoubtedly closely related but, so far as the present acquaintance- 

 ship with them suffices, presumably entirely distinct. Of the distinction between 

 the two, this seems to be indicated not only by the variation in general habit, 

 but is supported b}- the not too great, but still positive, differences in the 

 utricular structure. The utricles of Codium cerebriforme (see plate 39, figures 

 1—5) are of the compound or ramose type. A single primary utricle, usually 

 ver\' long and increasing in diameter with age, gives ofl" at successive heights 

 along its sides, spirally arranged, secondary utricles or utricular branches, and 

 this goes on until very complex groups (such as are partially represented in 

 our figures 4 and 5 on plate 39) are built up. In such groups of Tylecodium, 

 the primary utricle may be recognized, at least early, by its greater length, 

 greater diameter, and usually by its more profuse development of hairs (often 

 fallen and represented only by their basal scars). In larger (and older) utricle 

 groups, the earlier branches may assume the form and may possibly vie with 

 the original primary utricle in dimensions and branching. Such primary, and 

 even pseudoprimary, utricles are the ones to be described and measured as 

 typical of the species. The later utricular branches are usually shorter, more 

 slender, less modified at the apex and, especially, in the complexity of the 

 hair-forming zones. They are ever to be considered as more juvenile and are, 

 of course, much less typical of the species, often indeed much like those of 

 nearly related species. 



