DUBLIN MICROSCOPICAL CLUB. 205 
cation to be seen, but the specimens deserved a scrupulous exami- 
nation. 
Male Flowers of Dumorteuria irrigna.—Dr. Moore showed the 
male flowers of this plant. In Dr. Taylor’s account of the male 
receptacles in ‘ Flor. Hib.,’ part ii, p. 54, he states that “they are 
especially beset with short, straight, whitish hairs.’’ Dr. Moore’s 
specimen proved that these supposed short, straight, rigid hairs are 
flat hair-like scales, broad at the base and tapering to a sharp 
point; they are not straight, but much recurved in a radiating 
spiral manner round the base of the receptacle; they take their 
rise from the peduncle and cover over the greenish carnose portion 
amongst which the antheridia are placed when it is young, These 
flattish scale-like hairs formed a pretty object. 
Structure of Spines of Echinothriz turcarum and EH. calamaris. 
—Mr. Mackintosh exhibited sections of spines of the foregoing, which 
presented a wide diversity of structure. H. twrcarwm has the cen- 
tral hollow, which is moderate in size, surrounded by a solid ring, 
the lining calcification of the spine, with its usual foramina; next a 
zone of the reticulated tissue, bounded outside by an irregular ring, 
from which come off a number of elongate solid wedges, separated 
from one another by “ spokes” of reticulated tissue. The sections are 
of a beautiful pink colour, although the spines are dark red, nearly 
approaching to black. The spine of £. calamaris are banded white 
and brown, and in section show an exceedingly wide central hollow, 
occupied by a loose reticulation in injured specimens; next, there 
is the solid ring, but much less distinct than in H. turcarwm, 
and finally, on the outside, a series of solid pieces, shaped 
like an isosceles triangle, and joined here and there by transverse 
bars. As far as spine structure goes these two species tend in 
different directions; 2. turcarum having affinities towards Centro 
stephanus and Diadema, and EH. calamaris towards Astropyga, and 
the differences are sufficiently great as almost to justify Gray’s 
genus Garelia for EB. turcarum. However, the spines are said by 
Agassiz to vary greatly, at least in external appearance. He 
figures under the name L. calamaris sections which look exceedingly 
like those of 2. turcarwm, so that the question must be regarded 
as still swb judice. 
Crystalline Structure in Shrimp-shell—Mr, Porte exhibited 
sections of shell of shrimp showing a crystalline structure. He had 
been under the impression that the shell of crustaceans consisted 
of carbonate of lime segregated from the water and deposited, like 
chalk, in an amorphous condition ; having, however, accidentally 
examined a section of crab-shell by Topping, he perceived what 
seemed somewhat like crystals or calcareous dises arranged in 
tolerably regular intervals. It occurred to him that if he could 
obtain the shell of some very young crustacean, or, better still, the 
skin of one that had recently cast its shell, he would be able to 
ascertain whether the first deposit of lime were crystalline or amor- 
phous. Having by him some shells and skins of shrimps in various 
stages of development—none, indeed, in the exact condition he could 
