238 Correspondence. 



the sea, whicli shows a versatility not possessed by subaerial agents, 

 and which can breach through and overcome almost any exception 

 to its main mode of action. Many detached hills near escarpments 

 appear to be decapitated headlands, and can be at once explained by 

 the well-known tendency in the sea to enlarge bays laterally, until 

 connecting passages are formed. D. Mackintosh. 



Teignmouth. 



P.S. — As the work of excavation for villas proceeds, the proofs of 

 the marine denudation of the hills and valleys of the Torbay district 

 assume a more and more demonstrative character. On this subject 

 you will soon hear from me again. 



GRAPTOLITES. 

 To the Editor of the Geological Magazine. 



Sir, — I am sorry to have again to beg for a portion of your space, 

 but I am unwilling to let pass, without brief comment, certain state- 

 ments advanced by Mr. W. Carruthers in his letter on Graptolites 

 in your last number (page 187). 



I do not find it necessary to enter here into any further discussion, 

 as to the nature, or connexions, of what I consider to be the ovarian 

 capsules of the Graptolites. I am now in the possession of a large 

 number of specimens, proving, as I think, conclusively, that there 

 is, in some species, an actual organic connexion, and I trust shortly 

 to publish the results of my investigations on this point. 



As to the error, whereby Mr. Carruthers inserted the name of D. 

 Whitjieldii for that of D. marcidus, I should be inclined to think that 

 this change does not much improve his position, as D. marcidus 

 does not seem to agree with D. tricornis in anything except the 

 common character of possessing three processes at the base. 



Mr. Carruthers appears not to be fully acquainted with the true 

 nature of a "radicle," as defined by Hall, or, I think, he would not 

 assert that D. Whitjieldii is provided with more than one. The two 

 lateral spines, to which he alludes, are found in D. pristis, and in 

 various other species, and are simply processes from the first two 

 cellules on each side, and not " radicles " in any sense of the term. 

 My statement, that D. tricornis possesses three "mucrouate" radicles, 

 was simply made in deference to Mr. Carruthers's figure of this 

 Graptolite, where the nature of the lateral spines cannot be made 

 out ; and, also, on the supposition that he would not have chosen a 

 specific name expressive of a character common to several species. 



Mr. Carruthers still seems to think that the cellules in D. pristis, 

 of Hisinger, are mucronate. My assertion to the contrary, if wrong, . 

 is at any rate supported by all the descriptions of this species to 

 which I am able to refer. In neither the figures nor descrijations of 

 Salter, Hall, M'Coy, Harkness, or Geinitz, is there any mention of 

 anything of the nature of spines to the cellules of D. pristis. As 

 Mr. Carruthers has simply repeated his statement, and has not seen 

 fit to bring forward any proofs of its accuracy, he must permit me in 



