Dr. INlontagne on the genus Xiphophora. 261 



figm*e in Elirenberg shows a difference from the perfect plant so 

 much greater than in Micrasterias rotcita, that it looks like a 

 distinct species, and is in fact so considered in the ' American 

 Bacillarise/ 



Plate VI. fig. 2. Micrasterias Melitensis : perfect frond. 



XXXII. — On the genus Xiphophora, and, in connexion with it, 

 Observations on this question : Do we find in the Fucacese the 

 two Modes of Pi-opagation which we observe in the Floridese ? 

 By Dr. Moxtagne*. 



Xiphophora, Montgn., nov. gen. 



Frons sterilis, ex qua surgit fertilis (seu receptaculum), dichotoma 

 eaque brevior, compressa, flexuosa (en zigzag) apice truncata. Pars 

 maxima frondis in receptaculum planum, elongatum, dichotomum, 

 papulosum, olivaceo-nigrum, apicibus incurvis ensiformibus insigne, 

 abiens. Conceptacula immersa, per totam frondem fertilem sparsa, 

 globosa, poro pertusa, intus nucleum dimorphum foventia ; in altero 

 autem observantur sporae obovatae, luteo-brunnecP, limbo hyaline 

 cinctse, e cellulis parietalibus obortse, paraphysibus gracilibus articu- 

 latis simplicibus concomitatce ; in altero vero fila adsunt ramosa, ar- 

 ticulata, articulo extreme gemmam oblongam, granulosa repletam 

 materie, tandem liberam et perisporio, ut sporae genuinae, vestitara 

 includente. Habitus Ftici, at receptaculum Himanthalice, Nomen e 

 licpos, ensis, et 0epw, fero compositum. Prodr. nov. Phycear, in itin. ad 

 polum antarct. p. 12. t. 7. f. 1. 



Xiphophora Billardierii, jMontgn., I. c. 



Fucus gladiatus, Labill., PI. Nov. Holl. t. 256. 



Obs. — M. Hombron, principal surgeon of the Astrolabe, was 

 the first to find the fructification of this Alga. Previous to this 

 discovery, the plant from its habit had been ranked among the 

 species of the genus Fucus, where I would have left it, had it not 

 previously happened that the Fucus Loreus was separated on 

 grounds which ought to have the same value in the case of F. 

 gladiatus, Labill. In all the known species of Fucus, the recep- 

 tacle, elliptical or lanceolate, terminates the frond or the branches, 

 from which it is altogether distinct. Here we have, as in Himan- 

 thalia, a frond almost entirely converted into a receptacle ; and in 

 order to complete the resemblance, or at least the analogy, in- 

 stead of a sort of fungiform body from which the receptacle 

 originates, we find a frond very short, dichotomous, and remark- 



* From the Annales des Sciences Naturelles for October 1812. Trans- 

 lated and communicated by Dr. Dickie. 



