Geological Society. 141 



Echinolampas ovulum. Pericosmus Nelsoni. 



Holaster australise. P. compressus. 



H. difEcilis (Ehynchopygus dysas- Lovenia Forbesi. 



teroides). Euspatangus rotundus. 



Micraster breviatella. E. Laubei. 



Maretia anomala. E. murrayensis. 



Megalaster compressus. E. Wrightii. 



PericosDius gigas. Sehizaster ventrlcosua. 



A few notes were added on the relations between this fauna and 

 that now inhabiting the Australian seas, also on the connexions 

 with the Tertiary Echinoidea of New Zealand, Sind, &c. 



June 23, 1887.— Prof. J. W. Judd, F.R.S., 

 President, in the Chair. 



The following communications were read : — 



1. '• Note on some Dinosaurian Eemains in the Collection of A. 

 Leeds, Esq. — Part I. Omithopsis Leedsii. Part II. Omosaurus, sp " 

 By J. W. Hulke, Esq., E.R.S., E.G.S. 



Part I. OrnitJiopsis Leedsii, nov. sp., from the Kimmeridge Clay 

 of Northamptonshire. 



The Author described a pelvis, vertebrae, and costae referable to 

 this genus, of a stature far surpassing that represented by the 

 pelvis in the Pox Collection from the Isle-of- Wight Wealden, which 

 he brought under the notice of the Society a few years since. The 

 ilium has a very long preacetabxilar process. A rib is three times 

 as large as the largest rib of an elephant of average stature. The 

 trunk-vertebrae show the characteristic large chamber opening in 

 the side of the centrum, under the platform supporting the neura- 

 pophyses. There is no post-pubis. The pubis and ischium diverge ; 

 their close resemblance to those of Ceteosauriis oxoniensis, figured by 

 J. Phillips in the ' Geology of Oxford,' is obvious when each figure 

 is reversed, their true position being misrepresented in that author's 

 diagram, a very excusable error. 



Pakt II. described a sacrum, with ilia, vertebrae, a femur, &c. 

 The neural arches of the sacral vertebrae are synostosed, and so form 

 a continuous roof (simulating the vault of a cranium) of the dilata- 

 tion of the neural canal, which enclosed the sacral swelling of the 

 spinal cord. The transverse processes are long. The ilia offer a 

 general resemblance to those of Omosaurus armatus (Owen), but 

 differ from those of this species in the relatively greater length and 

 narrowness of the preacetabular process. The similarity of con- 

 struction of this sacrum to that of Stegosaurus, described by 0. C. 

 Marsh, and the very close resemblance of their ilia were noticed. 

 The author considered that an extremely close affinity exists between 

 these two genera, and is prepared to find that, upon the acquisition 

 of more materials, their identity may even be established. Eor the 

 present, he preferred to refer the Peterborough Dinosaur to Omosaurus, 

 and proposed for its specific name durobrivensis, having reference to 

 that of the old Roman settlement in that locality. 



