Geological Society. 119 



The zones of M. convolutus, M. argenteus, and M. fimhviatus con- 

 tain abundance of M. gmjarius, and the zone of Dimorpliograptas 

 confcrtus also contains Di^dograptus vesiculosus in considerable 

 numbers. 



The beds were also compared with the corresponding beds in 

 Sweden, Bohemia, Bavaria, »S:c., and the fossils other than Grapto- 

 lites were shown to occur elsewhere in strata of Llaudovery-Tarannon 

 age, from which it was concluded that the Stockdale Shales occupy 

 that horizon. 



A fault occurs everywhere between the Middle and Lower Skelgill 

 Beds, except perhaps in the Sedbergh district ; but it does not seem 

 to cut out a great thickness of rock, and the authors gave reasons 

 for supposing that it was produced by one set of beds sliding over 

 the other along a plane of stratification. 



The beds are found to thicken out in an easterly direction, and 

 the possibility of the existence of land in that direction was suggested. 



The authors directed attention to the importance of the Graptoli- 

 toidea as a means of advancing the comparative study of the strati- 

 fied deposits of Lower Palteozoic age. 



A descriijtion was given of the following new species and varieties: — 

 Pliacops elegans, Boeck & Sars, var. glaber, Cheimnis himucronatus, 

 Murch., var. acantJiodes, Cheirurus moroides, Acidasins erinaceus, 

 Harpes judex, H. angustus, Ampyx aloniensis, Proetus brachypggus, 

 and Atnjpa jiexuosa. 



May 23, 1888.— W. T. Blanford, LL.D., F.H.S., 

 President, in the Chair. 



The following communication was read : — 



" On the Skeleton of a Sauropterygian from the Oxford Clay, 

 near Bedford." By E. Lydekker, Esq., B.A., F.G.S. 



A description was given of a considerable portion of the skeleton 

 of a Sauropterygian from the Oxford Clay of Kempston, consisting 

 of several upper teeth, most of the mandible (of which the symphy- 

 sial region is entire), a considerable number of vertebrae mainly 

 from the " pectoral " and dorsal regions, the greater portion of the 

 two pelvic, and fragments of the pectoral limbs, and a considerable 

 proportion of the pectoral and pelvic girdles. These remains were 

 referred to Plesiosaurus philarcJms, Seeley, and the various parts 

 described in detail. 



The Author discussed the advisability of retaining the forms de- 

 scribed by various generic names by Professor Seeley, under the 

 name of Plesiosaurus, and stated his intention of employing the 

 latter term in its widest sense for the present. With this definition, 

 the form under consideration was shown to present characters 

 intermediate between those of Plesiosaurus and Pliosaurus, but was 

 retained provisionally in the former genus. Although a direct link 

 in the chain connecting the two genera, P. pUlarchus was not 



