HOLCOSPONGIA SULCATA. 229 
Sponges simple or in small irregular masses of three or more individuals. The 
basal portion flattened, or hollowed out where they have been attached to the 
convex surfaces of other bodies ; the dermal layer limited to the base. The single 
specimens are rounded or ovate, from 9 mm. to 18 mm. in diameter. The summits 
usually without a central depression; from the central portion a few deep open 
furrows radiate ; these are about 1 mm. in width. The skeletal fibres measured in 
a transverse section are from ‘1 mm. to ‘25 mm. in thickness. The rays of the 
axial spicules range up to -46 mm. in length. The filiform spicules are from 
‘005 mm. to ‘01 mm. in thickness ; their length could not be ascertained. 
To this species I have referred specimens from the Coral Rag of Malton which 
appear to agree with some of the forms figured by Quenstedt. They differ from 
H. polita, which comes from a slightly lower horizon, in the coarser character and 
closer arrangement of the skeletal fibres, and in the greater width of their canals ; 
and they are readily distinguishable from H. jloriceps. The specimens are usually 
simple forms, and not infrequently they are attached to the surfaces of Corynella 
Chadwichkit. (Pl. XVII, fig. 1.) 
Distribution.—Corallian. Coralline Oolite; zone of A. plicatilis, Langton 
Wold, Malton; Coral Rag, Settrington, Yorkshire. (Coll. Mr. 8. Chadwick.) 
Also in the Coral Rag at Nattheim. 
37. Hoxcosronaia sutcata, Hinde, sp. nov. Plate XVII, figs. 3, 3 a—h. 
Sponges simple, forming small fan-shaped, subcircular or ovate, recurved 
expansions, either directly attached by a small extension of the margin or by a 
short conical pedicle. Dermal layer slight, restricted to the base and the surface 
of attachment. The margins are rounded. On the front or upper surface of the 
sponge several well-marked, straight or curved, simple or furcate, open grooves 
radiate from a central area, in which there are one or two oscular apertures, but 
no definite depression. The grooves are from *75 mm. to 1 mm.in width ; they do 
not extend as a rule to the margins. The spaces between the grooves are occupied 
by the fibres and the irregular interspaces between them. (PI. XVII, figs. 3 a, 3c, 
3 e). On the lower or under surface of the sponge there is a series of grooves or 
furrows radiating fan-like from the point of attachment to the margin which they 
traverse, and sometimes reach to the upper surface, but they do not regularly 
connect with the canals of the upper surface. (Pl. XVII, figs.3,36,3d). These 
lower grooves are about ‘5 mm. in width; they are marked by elongated apertures 
about 1 mm. in length, which open into the interior of the wall. In young 
specimens the grooves appear rather as lines of apertures than continuous open 
furrows. 
GG 
