824 DR. G. J. HINDE ON RECEPTACULITIDS. 
and exhibit the structure more clearly than any of the calcitic 
specimens. 
The vertical spicular ray in Receptaculites (the cylindrical tube 
or hollow spicula of Billings; the Saulchen of Gimbel) is usually 
straight, and nearly cylindrical for the greater part of its length, 
but near its junction with the horizontal rays it somewhat suddenly 
contracts to form a short neck, and above this it expands and gives 
off the four horizontal rays already described, which are capped by 
the summit-plate. At its opposite extremity, the vertical ray is 
modified to form the substance of the inner layer. In most, if not 
all, of the species of Receptaculites, the vertical ray exhibits the same 
peculiar neck-like contraction. In none of the silicified specimens 
which J have examined are there any traces of the so-called 
‘‘intermediate small connecting stolons along the columns” mentioned 
by Salter *, which probably arise from chance fragments of silica in 
the interspaces between the columns. The surface of the vertical 
ray appears to have been smooth, although in some cases the mould 
exhibits slight transverse furrows, but whether these markings arise 
from the fossilization, or indicate constrictions in the rays, I am 
unable to determme. The vertical ray is also penetrated by an 
axial canal which connects with the canals of the horizontal rays 
above and with the horizontal canals of the inner layer below. The 
rays are, in conformity with the thickness of the specimen, relatively 
short near its nucleus, and of greater and nearly equal length in its 
central and peripheral portions. As seen in sections of decalcified 
specimens, the vertical rays appear as so many curved rows of 
vertical pillars, each of which is separated from those surrounding 
it by an interspace of about half its own thickness, and each spicule 
composed of the vertical and horizontal rays and the summit-plate 
is entirely independent except at itS basal end, where, as already 
stated, it is united to and forms part of the inner layer. 
The structure of the inner or upper layer of Receptaculites 
(endorhin of Billings; innere Hille, Gumbel) has not been ascer- 
tained so definitely as that of the exterior portion of the organism, 
owing to the rare cases in which it is preserved. The descriptions 
given of it by Dames and Giimbel, which have been taken from thin 
sections or etched surfaces of R. Neptuni, do not agree with those 
of Billings, which are based on the study of silicified specimens of 
R. occidentalis. In specimens of R. Neptuni from Belgium which 
I have seen, this inner layer is only shown in vertical sections as a 
thin delicate line of iron peroxide in which no structure whatever 
is visible; but in a Canadian example of apparently the same 
species, the inner layer, though only consisting of iron peroxide, 
exhibits well-marked perforations, the same as in R. occidentalis. 
Again, in another specimen of this species from Devonshire, the 
inner ends of the vertical rays appear to pass into circular or 
thomboidal plates, but I cannot determine if these are united 
together to form a continuous layer. 
In R. occidentalis, the inner or upper layer appears to be funda- 
* Canad. Org. Rem. dec. 1, p. 45, t. 10. f. 4a, 8. 
