Zoological Society of London. 285 



Interglacial Alluvium was of freshwater origin, but the admixture of 

 Scotch and Cumbrian detritus with that derived from the Pennine range 

 indicated that glaciers from the north again reached the Trent area. 

 A colder age succeeded, during which the Later Pennine Boulder-clay 

 was formed, partly of local materials, partly of erratics from the 

 Pennine range, mixed with a few from Cumberland and even from 

 Wales. This deposit was almost entirely unstratifie*!, and consisted 

 largely of moraine detritus, the ice -sheets having disturbed and re- 

 arranged the earlier deposits and mixed them with rock-detritus from 

 the neighbourhood. To this later ice-sheet was attributed the contor- 

 tion so frequently observed in the Older and Middle Pleistocene deposits. 

 Eeasons were given for the opinion that such contortions were due to 

 ice- and not to soil-cap motions or their later agencies. 



5. "On the Existence of a Submarine Triassic Outlier in the 

 English Channel off the Lizard." By E. N. Worth, Esq., F.G.S. 



Attention was called to the frequent occurrence of sandstone 

 fragments in a certain part of the English Channel, brought up by 

 the fishermen's " long lines." The evidence favours the idea that 

 these rocks are in situ. 



A list of the specimens found, with bearings and distances, was 

 given ; they consist of red, and sometimes greyish sandstones, mostly 

 soft, also marls, "potato stone," and nodules of Triassic trap. The 

 affinities are with the Keuper of Devon. The position deduced from 

 the observations is about 10 miles S.E. of the Lizard, and beyond the 

 30-fathom line. This submarine outlier is larger than any outlier on 

 the mainland of Devon or Cornwall, and carries the English Trias 

 nearly 50 miles further to the S.W. 



Zoological Society of London. 



April 20th, 1886.— Prof. W. H. Flower, LL.D., F.K.S., President, 

 in the Chair. — The following communication was read : — 



3. " On the Belations of the Mandibular and Hyoid Arches in a 

 Cretaceous Shark (Hybodus dubrisiensis t Mackie)." By A. Smith 

 Woodward, F.Gr.S. Communicated by the Secretary. 



Tn this paper, the author described the mandibular and hyoid 

 arches of Hybodus dubrisiensis, as exhibited in a fossil from the 

 Chalk of Kent, preserved in the British Museum. The cartilages 

 are all in an admirable state of preservation, and show that the 

 Cretaceous Hybodont skull made a near approach to the primitive 

 condition termed " amphistylic " by Prof. Pluxley (Proc. Zool. Soc. 

 1876, p. 41). The fossil jaws are also interesting from their close 

 resemblance to those of the Notidanidae, which are the most 

 amphistylic of living vertebrates ; and the pterygo-quadrate cartilage 

 exhibits the facette for a post-orbital articulation with the cranium, 

 which forms so characteristic a feature of the existing family just 

 mentioned. The hyoid elements are likewise remarkably slender. 

 The fossil further shows traces of well-calcified vertebras, which are 

 astero-spondylic in structure, and are well seen in a second specimen 

 in the National Collection. The latter fact is of peculiar interest, 

 since a fossil from the Lias, with teeth generically indistinguishable, 



