ete 
66 G. J. Brush on Tephroite. ‘ 
former and the latter; there is but one type of development in the 
medusoids of all the Hydroids. This is what my observations — 
within the past two years have led me to believe. The further 
development of the young of the Tubularians proceeds in an 
unequal degree for the different individuals, some of them grow — 
much more rapidly than others, and finally, becoming separated — 
from their matrix, move freely in the cavity of the genital orgal, — 
until their tentacles are developed so as to present the same one 
sided cylindrico-claviform outlines as the parent, and then the ie 
escape into the open sea. Thus they succeed each other unti 
the ovigerous layer is totally bereft of all its progeny, and noth: 
S eo 
ing but a faintly granular blastema is left to represent the outer 
wall of the proboscis, and its continuation the innermost wall of 
the bell. I would add finally, that in the males of these Tubu- : | 
Jarians, not even excepting Parypha, the meduso-genitals af — 
chap in form, structure, and development with those of the — 
emale: 
s ——e 
Art. VIl.—Contributions from the Sheffield Laboratory of Yale 
College—No. VI.—On Tephroite, by Gro. J. BRUSH. 
‘ ent of the original specimen in the collee 
tion of the Royal Mining Academy in Freiberg, and with thi 
neh ied 
ote oe STN 
I have been enabled to identify the species at Stirling, where it : 
occurs in considerable abundance. It has a distinct cleavage ae 
. . ? . 
varieties of willemite, which 
section; this permits its being readily distinguished from the 
l 
_ > Annals Lye. Nat. Hist., New York, vol. iii, (1828) p. 26 
: thaupt, Charakteristik des Mineral cat Bas ee 9. 
-* Stirling Hill is in the town of Spart System's, 3d ed., pp. 211, 32 
it so much resembles in color and 
