780 G. J. HINDE ON SOME FOSSIL CALCISPONGES FROM 
axial spicules are, as it were, imbedded is uncertain; they appear 
in the microscopic sections as thread-like lines running parallel with 
the directions of the fibres. Judging from the characters shown in 
other fossil sponges with fibres of a similar composition, but in a 
better condition of preservation, it seems probable that these 
filiform spicules are three-rayed, and that the rays are sinuous 
and unequal in Jength. Irregular spicules of this character have 
been described by Hackel in recent calcareous sponges. The 
complicated appearance which these marginal spicules exhibit in 
thin sections may be readily imagined if we suppose that their 
component rays are very closely interlaced together, which would 
render it nearly impossible to detect the individual spicules in a thin 
section through the mass. The dermal layer, which is only partially 
preserved in a few specimens, seems to have formed a delicate, thin, 
compact covering over the fibres of the basal and, in part, of the 
lateral portions of the sponge as well. As a rule, this layer has a 
smooth homogeneous aspect and bears a general resemblance to the 
so-called epitheea of fossil corals. It is a very rare circumstance that 
its spicular structure is preserved ; in fact it is only within the last. 
two years that its characters have been recognized, and it is there- 
fore remarkable that on some of these insignificant sponges its true 
structure should be clearly revealed. 
The absence of a cloacal tube and distinct canals brings this species 
under the genus Jnobolia, which is founded on the characters of a 
sponge irom the pea-grit beds of the Inferior Oolite at Cheltenham. 
In the typical species, however, only the relatively large axial 
spicules of the fibre can be recognized, the rest of the fibre being 
crystalline, whilst in the present species the marginal spicules of 
the fibre have also been preserved. This species differs from 
I. inelusa in form and in its much smaller dimensions. 
Distribution, Jurassic: Richmond, Surrey, 1205 feet beneath the 
surface. 
PERONELLA NANA, Hinde, n.sp. Plate XXXYV. figs. 2, 2a. 
Sponges small, simple, subcylindrical or inverted conical in 
form, probably attached by the basal extremity, the outer surface 
partially enveloped in a compact dermal Iayer. The type specimen 
is 5°2 millim. in length by 3°5 millim. in width, and the well-defined 
cloacal aperture at the summit is 1 millim. wide. 
The fibres, as seen in a transverse microscopic section, are 
relatively narrow, varying from -072 to -107 millim. in width; the 
spicular structure is not clearly exposed in the section examined, 
but traces of three-rayed spicules can be detected. On the surface 
of the dermal layer three-rayed spicules are faintly shown. 
Only two examples of this diminutive species were met with, and 
one of these was used in preparing a thin section. Judging by the 
similarity in size of these two individuals, it seems probable that 
they had attained their normaldimensions. The fibres, as shown in 
the thin section, are so crystalline that the spicular structure is 
largely obliterated, but it appears to be of a similar character to that 
