DUBLIN MICROSCOPICAL CLUB. 317 



being most perfect. The crystals were mounted in Klein's 

 dammar fluid. 



Trichomanes radicans. — Dr. McNab showed some preparations 

 illustrative of the Indusia and Sporani^ia of this fern. 



Structure of Spines of Strong yloeentrotus lividus. — Mr. Mackin- 

 tosh exhibited transverse section of a spine of S. lividus, showing 

 the main mass of the spine to be composed of a structureless 

 calcification of a pale yellowish colour, exhibiting striae, the 

 two most internal being the most distinct, the middle occupied 

 by a network of the ordinary echinoid structure, and proceeding 

 outwards from this to the deep but narrow furrows, which flute 

 the outside of the spines, are a number (twenty-two) of rays 

 ■which are also reticulated. One of these rays exhibited the 

 peculiarity of bifurcating a short distance from the circumference, 

 each prong going to a furrow, this ray was scarcely, if at all, 

 larger than its fellows, and there was not the least appearance 

 of asymmetry or irregularity in the ridge which its two sub- 

 divisions enclosed. 



Beryl Crystals ; sections exhibited. — Dr. Reynolds showed some 

 sections of beryl crystals from Mourne Mountains, exhibiting a 

 peculiar internal structure indicating a change of form during its 

 apparently interrupted growth. 



Head of Tcenia tetragonocephalus, exliihited. — Prof Macalister 

 showed the head of Tcenia tetragonocephalus, a parasite of the 

 maned anteater, Myrtnecophaga juhata. 



On Structure of Lmnhay PorpTiyry. — Prof. Hull, F.E..S., ex- 

 hibited two thin sections of Lambay Porphyry — one taken from 

 the rock at Lambay Island, the other from the opposite coast of 

 Portrane, north of Dublin. The examination of these under a 

 low magnifying power of twenty-five diameters showed that the 

 dark base was composed of felsitic material, more or less crystal- 

 line, containing large numbers of black crystalline grains of mag- 

 netite, together with a little chlorite. It was evident that the 

 dark colour was due entirely to the presence of magnetite, and 

 not to hornblende, as had sometimes been supposed. In this base 

 were included large crystals of orthoclase, giving the rock the 

 porphyritic structure. Some cells were seen to be lined with 

 chlorite and magnetite arranged in peculiar stellate or feathery 

 forms, whilst the interior was filled by calcite. The exhibition 

 was accompanied by excellently drawn figures by Prof. Hull, 

 illustrative of the structure of the rock. 



Exhibition of a preparation of and cursory remarks on, a 

 seemingly new and problematic Rhizopod. — Mr. Archer showed a 

 preparation in Beale's carmine fluid of a Rhizopodous form he had 

 encountered in various places, but always exceedingly sparingly 

 (he had hoped to show a recent example, but failed on this oc- 

 casion to alight on one). Tliis was quite globular, the inner 

 greyish or slightly yellowish body-mass surrounded by a colour- 

 less hyaline, thick, doubly-contoured envelope, marked by spar- 

 ingly scattered dots, which seemed to indicate so many tubular 



