138 Reports and Proceedings — Geological Society of London. 



The second genus and species are founded on a specimen in the 

 Grindrod Collection, obtained probably from the Silurian rocks, but 

 from a locality not known, possibly Dudley. In general appearance 

 it resembles an elongated form of Pisocrinus, particularly in its 

 calyx, but the arms are those of a Heterocrinid. This conjunction 

 of characters, though rendering necessary a revision of the definition 

 of the Pisocrinidee, cannot be regarded as bringing this family 

 appreciably nearer to the Heterocrinidse, which are fistulate, while 

 the Pisocrinidse, so far as known, are not. 



2. " Fossils in the University Museum, Oxford. III. A New 

 Worm-track from the Slates of Bray Head, Ireland ; with Observa- 

 tions on the genus Oldhamta." By W. J. Sollas, M.A., D.Sc, 

 LL.D., F.K.S., V.P.G.S., Professor of Geology in the University 

 of Oxford. 



The curious markings known as Ohlhamia have not been hitherto 

 recorded from other than the lower Paleozoic rocks, although they 

 have a wide distribution in space, being found in Ireland, in the 

 Ardennes, in Brabant, in America, and possibly in Norwaj'. While 

 the organic nature of Oldhamia was scai'cely a matter of doubt in 

 the minds of the earlier writers, there existed a great diversity of 

 opinion as to its place in the organic world, and it was placed 

 by different observers among polyzoa, hydrozoa, and plants, 

 respectively. The microscopical observations made by the author 

 prove that Oldhamia is not the remains of an organism, but merely 

 a marking in the rock, though one which might be, nevertheless, 

 of organic origin. Certain markings formed in the mud at Portishead, 

 by the feeding habits of a small burrowing crustacean, bear a con- 

 siderable resemblance to specimens of Oldhamia ; but a stronger 

 resemblance to the new species described in this paper is found in 

 Nathorst's figures of the impressions made by one of the two recent 

 worms Glycera alba or Gonidia macidata. Professor Joly's observation 

 that markings oi Oldhamia antiqua always occur in relief, while 

 those of 0. radiata are depressions, might suggest that while one set 

 of markings was produced by the animal when feeding, the other 

 was connected with its castings of excrementitious matter. This 

 explanation is open, however, to several objections, and the author 

 is inclined to believe that these species of Oldhamia are the traces 

 of some kind of siphonaceous alga : the cavities left by their decay 

 were subsequently filled in by sediment under pressure. If the 

 upper surface of 0. antiqua were more resistant than the lower, 

 this might account for its preservation in relief. The microscopical 

 examination of slate containing Oldhamia affords evidence of original 

 and secondary structures which have an important bearing on this 

 question. 



3. " Contributions to the Geology of British East Africa. Part 11: 

 ^ The Geology of Mount Kenya." By J. W. Gregory, D.Sc, F.G.S. 



The three main zones of Kenj^a are characterized by different 

 geological features. The long slope of the forest-belt consists in 

 the main of volcanic ash, though the remains of secondarj' parasitic 



