Geological Society. 545 



University Collection and three in the British Museum; all the 

 specimens come from the Carboniferous Limestone. The arms and 

 stem are at present unknown. The genus in general character and 

 structure recalls Platycrlnus, but the incorporation of the costal 

 and distichal plates in the calyx affords a very obvious distinction. 

 The analysis of the calyx, however, suggests the Melocrinidfe, from 

 the members of which it is chiefly distinguished by the comparatively 

 small size of the costal and distichal plates. The new genus is a 

 truly annectant form uniting the Melocrinidaj and the Platycrinid*, 

 and may be indifferently associated with either. 



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 tlie definition 

 of the Pisocrinidfe, cannot be regarded as bringing this family 

 appreciably nearer to the Heterocrinidse, which are fistulate, while 

 the Pisocrinidae, so far as known, are not. 



2. ' Fossils in the University Museum, Oxford : III. — A New 

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

 tions on the genus OkJhamia.' By W. J. SoUas, M.A., D.Sc, LL.D., 

 F.R.S., V.P.G.S., Professor of (jeology in the University of Oxford. 



The curious markings known as Ohlhamia have not been hitherto 

 recorded from other than the Lower Palaeozoic rocks, although they 

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

 Ardennes, in Brabant, in America, and possibly in Norway. While 

 the organic nature of Oh/handa was scarcely 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, respec- 

 tively. 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 formpd 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 Gli/cera alba or Gonidia macrdata. Prof. Joly's observation 

 that markings of Oldhamia antiquu 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 objeclions, and the Author 

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



Ann. i& Mag. X. Hist. Scr. 7. Vol. v. 35 



