PROCEEDINGS OF THE SOCIETY. 555 



more or less deformed, and one kind which was found on the top — 

 evidently a species of LojjJwhelia — was not like any other that he 

 had ever seen. Worms appeared to be numerous, and nearly every 

 one was found to be partly surrounded by coral. There were many 

 simple corals, and he noticed that their bases were much interfered 

 with by the worms getting out of the cable, and they seemed on that 

 account to have put out a number of small buttresses extending down 

 to the cable. He could never trace any portions of the worms which 

 had done this ; the cable had, however, been penetrated in varivjus 

 places by them. With regard to the very curious jaws described by 

 Mr. Stewart, there were found in the fossil state in the palseozoic 

 rocks objects which were called " Annelid Jaws " ; they had been 

 carbonate of lime originally, but he thought they bore no relation 

 either in position or structure to those which Mr. Stewart had 

 described — they were rather of the nature of grinding jaws. 



Dr. Matthews said that at the last Scientific Evening of the 

 Society he had exhibited some images of well-known forms (S and +) 

 produced in two ways. First, by the areolations of various diatoms 

 (such as Triceratium, Coscinodiscus, &c.). The second, by very 

 minute holes in thin laminse (such as tinfoil, &c.). 



In the first of these cases he had noticed that a very definite and 

 perfect focal image was formed, which was lost by focussing above, and 

 below, the focal plane. In the second case, although a very perfect 

 image was formed, yet no distinct focus was produced, the image 

 merely increasing or diminishing in proportion to the distance or 

 power of the objective by which the image was examined. The 

 inference he drew was, that nearly all diatoms were lenticular in 

 their areolations, since he had never discovered, by any power at his 

 command, in any diatom such a condition of image as at all 

 resembled that produced by the second of the methods employed. 

 He was well aware that this had been disputed, and he, therefore, 

 did not definitely assert that all diatoms were lenticular, but he 

 certainly thought that a strong case had been made out, by his 

 experiment, in favour of that view. 



Mr. Crisp said that both Mr. J. Deby and Count Castracane had 

 controverted the views of M. Prinz as to the existence of openings, 

 and he explained in detail the grounds on which their objections were 

 based (see p. 608). 



Mr, James Smith said he was some time ago examining a slide of 

 Pleurosigma formosum, and found the markings all distinctly separated 

 from each other, like chessmen on a board, looking like a plane with 

 a number of plano-convex lenses laid upon it. 



Mr. Beck said that whether the markings on P. angulatum were 

 elevations or depressions, it was quite certain that the cflfect described 

 could be produced by elevations. When minute globules of silica 

 were deposited from a solution, they formed a most perfect artificial 

 angulatum, and if they were obtained a little larger the hemispherical 

 globules of silex could be seen with the greatest possible plainness. 



