SPH^ROSPONGIA. 135 



present. The spicules vary from '36 to 1'5 mm. in diameter, and the rays are 

 from '033 to '137 mm. in thickness. 



Only detached spicules of this species have, as yet, been recognised in this 

 country, and these were discovered, sparsely distributed in decayed shaly lime- 

 stones, by Mr. John Smith, of Kilwinning. The spicules are all imperfect ; they 

 correspond very closely with those of the type form from the Glacial Drift of 

 Sadewitz, Lower Silesia, and with the detached spicules which I obtained from the 

 Isle of Gothland. They are now of calcite. 



Distribution. — Silurian : Wenlock shale, Wren's Nest, Dudley ; Dormington ; 

 Lincoln Hill ; Benthall Edge ; Malvern, at the west end of the Tunnel. 



Also in the Isle of Gothland and in the Drift of Sadewitz, Northern Germany. 



DEVONIAN SPONGES. 



Family. — Receptaculitidji. 



Genus. — Sph^rospongia, Pengelly. 



1861. Geologist, vol. iv, p. 340. 



Syn. — Sphaeronites, Phillips, F. Boemer, Bowerbank, Austin ; Echinosphserites, 

 Murchison, Keyserling, Verneuil ; Pasceolus, Kayser ; Polygonosphserites, F. 

 Roemer, Zittel. 



Generic Characters. — Pyriform, cup- or funnel-shaped Sponges, growing from 

 an obtusely-pointed, frequently incurved, base; without stem or attachment of 

 any kind. The summit in some specimens is dome-shaped and appears to have 

 been mostly inclosed, whilst in other examples it is widely open. 



The outer surface of the Sponge-wall consists of smooth, hexagonal plates, 

 regularly arranged in quincunx. Beneath the plates are the four transverse rays 

 of the spicules, which form vertical and concentric ridges on the inner side of the 

 Sponge-wall. An entering ray, like that in Ischadites, is either absent or only 

 represented by a short knob-like process. 



This genus was first referred by Mr. W. J. Broderip to the Tunicata ; then it 

 was placed by Prof. J. Phillips, as a Cystidean, in the genus Sphceronites, 

 Hisinger ; and subsequently Mr. Pengelly, who first discovered the characters of 

 the interior, described it as a Sponge, and constituted for it the genus Spharo- 

 spongia. Still later, the form was referred by Kayser to Pasceolus, Billings ; and 

 Ferd. Roemer, whilst recognising its relationship to Beceptaculites, Defrance, 



