378 Reports and Proceedings — 



The author referred to the genus Archimedes, recognized by 

 Lesueur, D. D. Owen, and James Hall, as a spiral form of Fenes- 

 tellid, the remains of several species of which occur in Lower Car- 

 boniferous Limestone rocks in the United States. In Archimedes 

 there is always a strong central shaft. The species here described 

 by the author under the name of Helicopora latispiralis occurs in 

 the Upper beds of the Niagara group of the Upper Silurian at Cedar- 

 ville, Ohio ; and the new genus is distinguished from Archimedes by 

 the absence of the solid stony axis above mentioned. Its character 

 as given by the author is as follows : — " Polyzoary expanded, fenes- 

 trate, and spiral, formed of slender, bifurcating branches poriferous 

 on one face, connected by non-poriferous bars forming an open net- 

 work ; cells arranged in two rows along the branches, one row on 

 each side of a median keel. Axis very thin, or consisting only of 

 the thickened central border of the spiral polyzoary." The species 

 described grows to as much as eight inches in diameter. The 

 author has seen a second species of the genus. 



IL— June 21, 1882.— J. W. Hulke, Esq., F.E.S., President, in the 

 Chair. — The following communications were read : — 



1. " On Thecospondylus Horneri, a new Dinosaur from the Hastings 

 Sand, indicated by the Sacrum and the Neural Canal of the Sacral 

 Eegion." By Prof. H. G. Seeley, F.R.S., F.G.S. 



The author described a mould of the neural canal of the sacral 

 region of a Dinosaur, obtained by Dr. A. C. Horner, of Tunbridge, 

 fVom a quarry in the Hastings Sand at Southborough. The specimen 

 is about 2 feet long, slightly imperfect at both ends, but showing 

 indications of five complete vertebra, with traces of others at the 

 two extremities, making at least seven vertebrae in all. The general 

 form of the neural chamber is compressed from side to side, and 

 dilated from below upwards, especially in the region of the second, 

 third, and fourth vertebree, its depth over the third foramen being 

 nearly 3^ inches. Indications of bone preserved on the surface seem 

 to shovv^ that the neural canal was inclosed in a mere bony film. 

 The indications of transverse processes show that they were directed 

 forward in front, outward in the middle, and backward behind. 

 The first process on the right side, which is preserved, expands 

 somewhat conically outwards and forwards, and terminates in a large 

 flattened facet for the ilium. For the animal indicated by this 

 specimen the author proposed to found a new genus, Thecospondylus, 

 and named the species T. Horneri. 



2. " On the Dorsal Region of the Vertebral Column of a new 

 Dinosaur, indicating a new genus, Sphenospondylus, from the Wealden 

 of Brook, in the Isle of Wight, preserved in the Woodwardian 

 Museum of the University of Cambridge." By Prof. H. G. Seeley, 

 F.E.S., F,G.S, 



In this paper the author described a series of six vertebrae, re- 

 markable for the great lateral compression of the centrum, which is 

 so narrowed inferiorly as to terminate in a sharp longitudinal ridge. 

 The centra average about 3^ inches in length. The neural arches 



