CORRESPONDENCE. 187 



problem of tliis mysterious boring question. I at once wrote off to a 

 friend in London for the ' Journal of the Quekett Microscopical Club.' 

 The return of post brought me the wished-for paper. I sat down at 

 once and read it, and, Sir, what do you think my exclamation was 

 when I had finished? why, like Charles Mathews in his celebrated 

 character in "Used Up": he is supposed to have ascended Mount 

 Vesuvius, and when asked what he thought of it, he simply said 

 " there ivas notliing in it" and certainly there was nothing new in it. 

 I cannot see that Mr. Waller has brought forward one single scrap 

 of evidence to bear out his assertion that the Cliona does not make 

 the excavations in which it dwells ; he says that the holes are made 

 by annelids ; in some cases he is right, annelids do occasionally 

 cross the path of a sponge, and the sponge takes advantage of the hole 

 bored, or, as I lave stated in my paper, " eroded." 



When I was writing that part of my " Catalogue Fauna of Devon " 

 containing the Spongiadse, some hundreds of specimens passed through 

 my hands, and each of these had to be critically examined. I conse- 

 quently collected a mass of materials, and those bearing on the 

 " boring " problem I used last year in the paper referred to. 

 Mr. Waller says " we cannot possibly imagine a structure so feeble 

 capable even of conveying the power of excavating at all without an 

 entire subversion of the mechanical law, viz. that an effect cannot be 

 greater than its cause. The feeble, simple character of this organism 

 seems indeed to give us reason of its seeking for protection in holes 

 and corners from external attacks." 



We will place by the side of this two or three vegetable organisms, 

 which I think will be admitted by all who know them that they are 

 equally as feeble, if not more so, than this Clione in dissolving or 

 burrowing into shell and rocks. The first, then, is Verrucaria suh- 

 liitoralis, Leighton, which, curious enough, selects one or two species 

 of acorn-shells for its habitation, the shells of which are some- 

 times very thickly perforated by it ; and when the perithecia have 

 fallen out of these holes, which they do when they get dry, and are 

 sometimes washed out by the waves, and one seeing the shells then 

 would declare they had been bored by some annelid. Pultney, and 

 afterwards Montagu, both called one of these acorn-shells Balanus 

 punctatiis, thinking it peculiar to the species. The perithecite have 

 the power of dissolving the shell and almost burying themselves in it. 



Again, Verrucaria calciseda, D.C., has the power of sinking or 

 burying its perithecise in the otherwise solid rock. And my friend 

 Mr. H. J. Carter, in ' Ann. Nat. Hist.,' vol. v., dth series, p. 79, says, 

 in discussing Grayella, Osculina, and Cliona, " Undoubtedly, too, if 

 the almost liquid mysogasters can work their way through hard w^ood 

 to the surface ; if the like delicate endophytes Chytridium, Pythium, 

 &c., can pierce the horn-like coverings of Algfe, and the soft cell of 

 Zygnema can dissolve its prison walls for exit and conjugation, the 

 amoeboid sponge can burrow amongst the layers of an oyster-shell for 

 its subsistence." I think this is sufficient evidence to prove that 

 equally feeble organisms have quite as great powers of working as is 

 attributed to the industrious annelids, and the siipposed indolent 

 Clionas. 



