270 



THE GEOLOGIST. 



Salter, Esq., F.G.S., etc. Of this form an imperfect individual, from the 

 anthracite- shales (Llandeilo flags) of Dumfriesshire, was formerly described 

 by the author as Dicthyrocaris ? aptycJioides. Better specimens enabled 

 him to distinguish it as a new generic form belonging to the Phyllopods, 

 not far removed from Hymenocaris and Dithyrocaris. A fragment of an- 

 other larger form, from the same locality, is described by the author as 

 Peltocaris ? Harlcnessi. Mr. Salter also explained his views of the rela- 

 tionship of the palaeozoic Tliyllojpoda, among themselves and with the re- 

 cent forms, and illustrated them by a diagram in which they were ar- 

 ranged in chronological succession. 



6. " On a Crustacean Track in the Llandeilo Flags of Chirbury, Shrop- 

 shire." By J. W. Salter, Esq., F.G-.S., etc. This track consists of nume- 

 rous short, narrow, oblique, chisel-shaped imprints, on the ripple-ridges of 

 the slab ; and, according to the author, it must have been caused by a small 

 Crustacean with a bifid telson or prong-like tail. To a like agency Mr. 

 Salter refers similar markings described by M. Brebisson as occurring in 

 the Lower Silurian Sandstone of Noron in the Falaise (Normandy). 



June 4. — The following communications were read :— 



1. " On the disputed aifinities of the Purbeck Mammalian genus 'Pla- 

 giaulaxr By Hugh Falconer, M.D., F.E.S., F.G.S. 



Referring to his former description (Journal Geol. Soc , vol. xiii. p. 261, 

 etc.) of Plagiaulax as a rodent form of marsupial, having affinities with the 

 existing Hypsiprymnus ; and to the very different opinion of its relation- 

 ship expressed by Professor Owen in the 8th edition of the ' Encyclopsedia 

 Britannica,' where it is said to have been " a carnivorous marsupial," Dr. 

 Falconer then reviewed the dental characters of Plagiaulax in detail. 

 The incisors, in regard of number, order of suppression, collateral position, 

 and relation to the premolars, correspond exactly with the type of marsu- 

 pial herbivora, and are wholly at variance with the carnivorous type ; and he 

 argued that Professor Owen's argument drawn from Thylacoleo has no 

 bearing on the incisors of Plagiaulax, and gives no support to the car- 

 nivorous inference. Of the premolars, after a full comparative re-exami- 

 nation (in agreement with his already published views) he finds reason to 

 regard the carnivorous deduction from the shape of the premolars to 

 be altogether untenable. 



The form of the lower jaw of Plagiaulax having been regarded by 

 Professor Owen as conforming with the carnivorous type, the author 

 sliowed that in the non-carnivorous Cheiromys (Aye-Aj^e) and Plias- 

 colarctus (Koala) a similar form of ramus obtains ; and that the coronoid 

 and condyle of the Aye-Aye are not unlike those of Plagiaulax ; whilst 

 in existing predaceous marsupials the condyle has a different form. The 

 author considered that Plagiaulax was essentially a phytophagous mar- 

 supial. 



2. " On some Fossil Plants from the Hempstead Beds, Isle of Wight." 

 By the Eev. Dr. O. Heer, Professor of Botany, Zurich. With an intro- 

 duction, by W. PengcUy, F.G.S. 



These pUiiit-romain'fe, from the Hempstead Series, consist of seeds, 

 cones, loaves, and l\\ io,s, and are referable to ten species, four of which 

 have been found latrly at Bovey Tracey also, namely, Sequoia Coidtsice, 

 Hoor, Andromeda rdiruh'la, Ettin., Nymph(Ea Doris, Heer, and Carjyo- 

 lifcs Wrhsfcri. Brongn. Tlu^ other species are Cijperites Forhesi, n.s.,Nelu}7i- 

 hinm linchii, Ettin., CarpolUcs ,ilnhiilus, n. s.', Chara Escheri,^TA\m, and 

 Ch. tuhcrculata, Lyell, var. I'lorcssor Heer notices that six of the above- 

 named .>^i)ocies are found also in the Lower Miocene (Tongrian and Aqui- 

 iauian) of the Continent ; and that this flora, as far as represented, seems 



