PEATE, 
Figs. 1, 1 a—ProrosponGIA FENESTRATA, Salter. 
Fig. 1—A fragment of the spicular-mesh of the Sponge-wall, embedded in hard black slate. 
Natural size. From Menevian strata, St. David’s, South Wales. Drawn from the type example of 
the species, now in the British Museum (Natural History). 
Fig. 1a.—A portion of the spicular-mesh of the same specimen, magnified five diameters. The 
original regular arrangement has been partly broken up, and owing to the cleavage of the rock the 
angles of the spicules are distorted. 
Figs. 2, 2¢.—Prorosponoia Hickst, Hinde, sp. nov. 
Fig. 2.—The compressed Sponge-wall, traces of which can be seen covering the surface of a slab 
of dark shale. Natural size. From Menevian strata, Porth-y-Rhaw, St. David’s, South Wales. 
Drawn from the type specimen, in the Woodwardian Museum, Cambridge. 
Fig. 2. a.—Portion of the spicular-mesh of the same specimen in an imperfect condition. Magni- 
fied five diameters. 
c \ lo 
Figs. 3, 3a, 36.—Hyatostenia Fascicunus, IOoy, sp. ~~ — 
Fig. 3.—Portion of the anchoring-rope of the Sponge, showing the parallel disposition of the 
component spicules. Natural size. Probably from Llandeilo Rocks. Original in British Museum 
(Natural History). 
Fig. 8 a.—Transverse section of the same specimen, enlarged ten diameters. 
Fig. 36.—Portion of the rope, enlarged ten diameters, showing the annular or spiral frills on the 
spicules. 
Figs. 4, 4a.—Hyatosteria Smiruit, Young and Young, sp. 
Fig. 4.—Portion of the rock, showing the size and the distribution of the anchoring-spicules 
in transverse section. Magnified five diameters. From Ordovician shale at Knockgeiran, near 
Girvan, Ayrshire. The original specimen in the collection of the author. 
Fig. 4a.—A longitudinal section of the rock, showing the spicules, which have been cut through 
obliquely. The transverse bands in them arise from the replacement of the silica by a mineral of a 
different aspect. Magnified five diameters. 
Figs. 5, 5 a—5 f—Hyaxosterta eraciris, Hinde, sp. nov. 
Figs. 5, 5 a—e.— Hexactinellid spicules, with the normal number of rays, though mostly imperfect. 
Figs. 5 d, e—Cruciform spicules, rays all unequal. In 5e they are spinous. 
Fig. 5 £—Microspined cylindricai rods, probably belonging to the anchoring spicules of the Sponge. 
All magnified forty diameters. From decayed Wenlock limestones, Craven Arms, Shropshire. The 
origina] specimens in the collection of John Smith, Esq., Kilwinning, Ayrshire. 
Figs. 6, 6a—6 d.— ATRACTOSELLA SILURIENSIS, Hinde, sp. nov. 
Detached fusiform spicules, referred to this species. The specimens are siliceous; 64a, b, are 
partially encrusted with matrix. Magnified forty diameters. From Wenlock limestones, Craven 
Arms, Shropshire. The original specimens in the collection of John Smith, Esq., Kilwinning. 
Figs. 7, 7a—7 d—Astrxosponata Patina, F Roemer. 
Detached spicules of this species, the rays in all cases imperfect. In Figs. 7a, 6,c, only the six 
horizontal rays are present, in Fig. 7 one ray of the vertical axis is developed, whilst 7 d represents an 
abnormal form in which only half the number of the horizontal rays is developed. Magnified forty 
diameters. From Wenlock shales at Wren’s Nest, Dudley, and at Benthall Edge, Shropshire. The 
original specimens in the collection of John Smith, Esq., Kilwinning. 
