DUBLIN MICROSCOPICAL CLUB. 195 



far as he was aware, although both Mr. Phillips and Mr. Yize 

 had informed him that they possessed specimens of it. It forms 

 a delicate pinkish-grey bloom on the surface of the wood, con- 

 sisting of numerous short threads, bearing spiral heads of 

 rather oblong spores. It differs from Helicomyces tuherosus, 

 figured in ' Grevillea ' (vol. iii), in having longer heads, which 

 are in length about twice the diameter of the spirals ; in having the 

 spores in a flat, not a helicoid, spiral ; in having the spores them- 

 selves more oblong than square ; and in its pink rather than white 

 colour to the naked eye. 



A Vertical Section of the Frontal Lohe oftJie Gerehrum in Young 

 Chick, prepared by Professor Cleland, was exhibited by Dr. 

 Macalister. 



Floelerg Bust, exhibited. — Dr. Moss, late of H.M.S. 'Alert,' 

 showed samples of " Ploeberg Dust," collected on the late Arctic 

 Expedition, and containing remains of diverse microscopic organ- 

 isms — Diatomaceae, Eadiolaria, Peridinium sp. — some from a 

 mass of interesting material he had yet to work up. 



Sections of Erectile Tissue, exhibited. — Mr. B. Wills Richard- 

 son exhibited several sections taken from the penis of a child aged 

 three and a half years. They formed that portion of the organ 

 situated between the glans and the scrotum, and were made with 

 the freezing microtome, stained with Beale's carmine stain and 

 mounted in glycerine. Mr. Richardson drew particular attention 

 to the shape of the urethra in the specimens. It was not tubular as 

 some persons imagined ; and in the portion of the organ which 

 afforded the sections was a transverse slit or fissure, with shorter 

 fissures leading from it. That disposition of the canal showed that 

 it was plicated in the longitudinal direction, an arrangement ap- 

 parently to allow of its expansion for the free ejaculation of the 

 semen. In none of the sections could a helicine artery be dis- 

 covered in the corpora cavernosa. 



Tooth of Echinothrix turcarum. — Mr. Mackintosh exhibited a 

 cross section of the tooth of Echinothrix turcarum, Schynvoet ; 

 also some of the detached prisms, covered with " soldering 

 particles," and a separate " flabelliform process " of the same. 

 The principal point in which the tooth-structure of this species 

 differs from that of Echinus, so well described by Salter (' Phil. 

 Trans.,' 1861), is in the absence of a keel on the internal aspect, 

 the tooth being simply grooved, and the consequent reduction in 

 the amount of the prismatic tissue, which occupies a compara- 

 tively narrow zone in the middle of the tooth. 



New form of Donkinia. — Rev. E. O'Meara showed what ap 

 peared to be a new form of Donkinia, found in stomach of 

 Ascidians cast on the shore of Dublin Bay by recent storms. 

 Valves short and broad ; height -0035" ; breadth "0066" ; broad 

 and rounded at ends ; striae coarse, oblique ; median line diago- 

 nal, approaching closely to the margin at either end, and in an 

 opposite direction. On f v. slightly constricted in the middle ; 

 lobes nearly linear till near the ends ; striae obvious. 



