il 



Mr. Gar.uthcrs prefers to compare the plant as to stmcture 

 with cer'.aiD chlorospermous Algae, and us to size with certain 

 gigantic Melanospcrms, not pretended to show similar structure. 

 This is obviously a not very scientific way of establishing affini- 

 ties. But let us take his grounds sep.irately. He selects the 

 little jointed calcareous sea-weed ILilimcdii opuntia, as an 

 allied structure, and copies from Kutzing a scarcely accurate 

 figure of the tissue of the plant as seen after the removal of its 

 calcareous matter.* He further gives u defective description of 

 this structure; whether taken from his own observation or from 

 Kutzing, ho does not say. Harvey's description, which I verified 

 several years ago, in an extensive series of examinations of these cal- 

 careous Alg«3, undertaken in consoquenceof a suggestion that Eo- 

 zocin might have been an organism of this nature, is as follows: — 

 " Aftur the c ilc ircous matter of tlie frond has been removed by acid 

 a spongy vegetable structure remains made up of a plexus of slender 

 longitudinal unicellular filaments constricted at intervals, and at 

 the constrictions emitting a pair of opposite decompound, dicho- 

 tomous, corymboso-fustigiate horizontal ramelli, whose apices co- 

 here and form a thin epidermal or peripheric stratum of cells." 

 It will be seen at once that this structure has no resemblance 

 whatever to anything existing in Prototaxites, even as interpreted 

 by Mr. C, and without taking into account the fact that Hall- 

 vicdn opuntia is a small calcareous sea-weed, divided into flat 

 reniform articulations, to which this structure is obviously suited^ 

 as it would be equally obviously unsuited to the requirements of 

 a thick cylindrical trunk, not coated with calcareous matter. 



In point of size, on the other hand, Mr. Carruthers adduces 

 the great Lcssonia of the Antarctic seas, whose structure, how- 

 ever, is not pretended to resemble that of Prototaxites except in 

 the vague statement of a pseudo-exogenous growth. Lcssonia I 

 have not examined, but the horny Lamuuiria' of our North 

 American seas have no resemblance in structure to Prototaxites. 



Nothing further, I think, need be said in reply to Mr. Car- 

 ruthers' objections; and Ncmatophj/cus may be allowed to take 

 its place along with a multitude of obsolete fucoids which strew 

 .he path of palaeontology. As to Prototaxites, it is confessedly 

 an obscure and mysterious form, whose affinities are to be dis- 



• A more characteristic figure is given in Harvey's "Nortli Ameri- 

 can Algaj." 



