816 DR. G. J. HINDE ON RECEPTACULITIDZ. 
Genus SpHarRosponera, Pengelly, 1861, Geologist, vol. iv. p. 340. - 
1841. Spheronites, Phillips (non Hisinger), Pal. Fossils of Devon 
and Cornwall, p. 135. 
1861. Spherospongia, Salter, pars, Memoirs of the Geological 
Survey of Great Britain. The Geology of the Neighbourhood of 
Edinburgh, p. 136. 
1875. Pasceolus, Kayser (non Billings), Zeitschr. d. deutsch. geol. 
Gesellsch. Bd. xxvii. p. 776. 
1880. Polygonospherites, F. Romer, Letheea Palozoica, Th. 1. 
p. 296. 
The typical example of this genus, on which Phillips bestowed 
the name Spheronites tessellatus, is now preserved in the Jermyn- 
Street Museum, and from this, and other examples of the same 
species from Devonshire, the characters described below have been 
ascertained. The form of the original specimen is incomplete; it 
appears to have been pear-shaped, but as only a portion of the dome- 
shaped summit is preserved, it is difficult to determine whether 
it possessed an entire roof, or whether there was a central aperture, 
as in [schadites. Other specimens are open, cup- or funnel-shaped, 
gradually curving towards the base, which terminates in a small 
bluntly-rounded extremity with no appearance of stem or roots, 
so that these fossils were clearly free and unattached. ‘The funnel- 
shaped specimens are frequently hollow, the peculiar granular 
crystalline matrix not having penetrated into the interior cavity, 
but their upper surfaces are Invariably obscured by the matrix, so 
that I have been unable to ascertain whether these organisms had a 
complete dome-shaped roof or not. 
The outer surface is composed of an apparently close-fitting covering 
of spicular head-plates of hexagonal form (Pl. XX XVII. figs. 1, 1d); 
but though the margins seem to be in intimate contact, narrow 
linear spaces filled with the matrix are occasionally visible between 
them, and these interspaces are very generally shown in the granu- 
lar crystalline examples. The spicular plates are somewhat smaller 
in the basal portion, but in the middle and upper portions of the 
organism they are tolerably uniform in size, and, for the most 
part, regular hexagons in figure. The plates im the type specimen 
are smooth on their upper surface, nearly flat, and with a small 
central rounded elevation, which is only seen in the best-pre- 
served specimens; in the majority of examples no trace of it is 
shown. They also exhibit numerous fine concentric lines, resembling 
lines of growth, and occasionally their margins are slightly elevated, 
sufficiently in some cases to cause a slight depression between the 
margin and the central protuberance. No structure can be seen in 
these head-plates, and their thickness appears to be inconsiderable. 
They are arranged in an extremely regular quincunx. 
In the hollow specimens (Pl. XX XVII. fig. 1 a) the interior surface 
immediately beneath the summit-plates, is divided into oblong and 
quadrate spaces by vertical and transverse ridges. The vertical 
ridges run from the base to the upper portion of the specimen, 
