liev. jM. J. Berkeley 0/i Fucus Labillardierii. 59 



but radiating from a basilar or axillary placenta. These plants 

 agree indeed in external habit and in the form of the tetraspores, 

 though not in their disposition, but their internal structure for- 

 bids their association in the same tribe. Delisea, by the struc- 

 ture of the frond and conceptacula, must be arranged with Chon- 

 driea ; and as Ctenodus cannot be arranged in any of the tribes 

 hitherto established amongst Floridea>, I am compelled to form 

 a distinct tribe for it, under the name of Ctenodontees, on which 

 I purpose shortly to present a memoir to the Institute. 



" The tetras]>oric fruit consists of oblong or spheroidal, shortly 

 pedicellate receptacles {pohjthecid) situated at the axillse of the 

 pinnules which fringe its branches. The most cmious point is, 

 that these receptacles contain not spores but tetraspores, alto- 

 gether analogous to the compound sporidia of certain genera of 

 Lichens, or even Fungi. I have no hesitation in asserting that 

 this mode of fructification is of very high importance for science 

 and very instructive. The interior disposition of the tetraspores 

 is as follows : — The capituliform summit of the fructifying ra- 

 mule (or, in other words, the receptacle,) is divided into periphe- 

 rical, ovoid, or spherical cavities. In a vertical section passing- 

 through the axis five or six of these cavities are observed, and the 

 number in the whole receptacle amounts perhaps to fifteen or 

 twenty. These cavities have a great analogy with those of Fu- 

 cacece, by the place the tetraspores occupy, by the form of these 

 tetraspores (with the exception of their articulation), and, what 

 is still more worthy of attention, by their convergent direction, 

 which are accompanied by paraphyses, or, in other words, by 

 abortive tetraspores. The question indeed would not be one 

 of analogy but of perfect resemblance, if the spores were sim- 

 ple instead of being compound. Short continuous filaments 

 converging towards their centre proceed from all points of the 

 cavities, at least in the first stages of evolution, for in the adult 

 state the portion of the cavity corresponding with the cortical 

 stratum of the receptacle is unoccupied. The greater part of 

 these filaments, which are clavate and branched at the base only, 

 remain sterile and transparent (jjarap/iT/ses) ; a few privileged 

 individuals undergo a metamorphose of the granidar line which 

 occupies their axis, in virtue of which they become compound 

 spores. At first simple and continuous, oblong and conform- 

 able to the tube of the thread which performs the functions of 

 a perispore, the tetraspore is gradually furrowed by three trans- 

 verse lines, by which at maturity it is divided into four spores. 

 These separate, fall into the cavity, and probably are not dispersed 

 before the decay of the receptacle, for I have not been able to 

 find any pore which may serve as a natural outlet. In this sin- 

 gular fructification we sec most evidently that the filaments in 



