Dublin Microscopical Club. 341 



Nordstcdt's Brazilian species could be truly the same as the Swedish 

 and Irish one, which were precisely identical ; the former is smaller, 

 and cannot be at all so noble an object. At first glance so fine a thing 

 is most striking ; and when first noticed, Mr. Archer, attracted by the 

 three conspicuous spines at the angle, was momentarily under tho 

 impression that he had encountered S. Roi/anum in Ireland, itself a 

 large and fine species, but still a good deal smaller than S. brasiliense ; 

 but a second glance showed the mistake, and S. Roj/mmm still re- 

 mains undetected out of Glencoe, in Scotland ; nor did a search there 

 on the occasion of a visit in the autumn of 1880 redisclose it. 



April 16, 1880. 

 Pandorea Traversil, J. Ag. — Prof. E. Perceval Wright showed a 

 preparation of Pandorea Traversil, J. Ag. species, for which he 

 was indebted for specimens to Prof. J. G. Agardh. It seems to 

 show some interesting points of resemblance between the structures 

 long since described to the Club in the young growing fronds of 

 Griffithsia setacea by Dr. AVright. 



The " functa " distributed over the smooth cell-tvalls of Desmidieoe 

 are really pits or depressions, not thickenings or points different in 

 tint from the rest of the membrane. — Mr. Archer brought under 

 notice some empty cell-walls of Cosmarium pyramidatum and some 

 other Desmidieae, in order to draw attention to the " puncta " or 

 dots covering the superficies, with a view to show that these puncta 

 are really depressions or pits, not either mere darker, or brighter, or 

 thicker points of the wall or membrane. Whether these depressions 

 might not sometimes represent tubules passing right through, ho 

 would leave in abeyance. That they really indicate hollows or pits 

 is, in minute forms very " finely punctate," somewhat difficult of 

 verification ; but on looking over a series of the " smooth " forms, 

 as the puncta become more and more " coarse " the fact seems very 

 readily made out, until in such large forms as the larger Euastra 

 they appear, especially on the inflated prominences, decided minute 

 cup-like hollows. It may be, indeed, that these pits may present 

 the appearance of having become filled with some more solid sub- 

 stance, like a kind of excretion through siich openings, giving some 

 forms a pseudogranulate aspect. May it be possible that the radi- 

 ating lines noticeable in the enveloping mucous investment of many 

 of such forms stand in direct connexion with these " pimcta" ? and 

 may such lines represent tubules carried on through such mucous 

 coat ? Forth from these radiating lines or striae in the mucus, which 

 naturally stand vertically to the superficies of the cell-membrane, it 

 is that " Bacterium-VikQ^^ (to bene more precise) bodies may some- 

 times (though the occasions are rare) be seen to issue, and aU the 

 more readily on application of some pressure on the covering-glass, 

 and then slowly totter off- — a fact that probably has not been gene- 

 rally noticed. The nature of the puncta and markings in general 

 on the Diatoms has often been the subject of dispute ; but no one 

 seems to have paid much attention to test what the nature of the 



