100 REPORT — 1873. 



pala30]itologists ; and if some fifteen or twenty of tliese be suppressed, tlie number 

 ■will have been more tbau doubled since 1853. 



Mr. Davidson observes that it is also curious to notice that a general, but not 

 regular decrease in the number of species has taken place since the Palseozoic era 

 up to the present time, and that many j-ears must elapse before paljeontologists 

 "will be able to clear away the many difficulties that still prevent their arriving at 

 a truly satisfactory classihcation of the group. 



Hemarls on ilie Genera Trimerella, Dinobolus, rtiicZMonomerella. By Thomas 

 Davibsoit, F.B.S. cJt., and William King, Sc.D. and Professor of Minera- 

 logy and Geology in Queen's College, Gcdwaij. 



The paper touched upon some of the salient points treated of in a detailed memoir 

 in preparation by the authors for the Geological Society. They propose the name 

 TrimereUida for a family to include the genera named in the "title. The typical 

 genus Trimerella, although possessing many distinctive features, is in their opinion 

 structurally and genetically related to Lingida. Reserving the discussion of the 

 first of these points to their forthcoming memoir, they gave reasons for holding 

 the view that Trimerella has been created, adopting the doctrine of gcnetheonomy, 

 out of some preexisting Liugulid. The internal features, most complex in tlie 

 type genus, were briefly noticed ; and their modifications, as characteristic of the 

 three genera, were pointed out. 



The chronogeological range of the family extended from the Llandeilos to the 

 "Wenlocks, the latest and only representative species of Dinobolus occun-ing in th^ 

 latter rocks. The known species have been found in Canada, the United States, 

 Gothland, Eussia, and England : Dudley is the only English locality. The family 

 comprises about seventeen species, which have been instituted by Billings, Lind- 

 strom, Hall, Meek, Dall, Salter, and the authors. 



On the rii'/sical Geor/rapln; of the Mediterreineetn during the Pleistocene Age. 

 Bij W.' Boyd Dawkixs, M.A., F.R.'S. 



The geological evidence that the area of the MediteiTanean has been subjected 

 to oscillations of level during the tertiary period, is clear and decisive. Professor 

 Gaudry has proved, in his gi'eat work on the fossil remains found at Pikermi, that 

 the plains of Marathon mutt have extended far south into the Mediterranean, in 

 the late Miocene period, to have supported the vast troops of Hipparions, herds of 

 antelopes, and the very remarkable Mastodons and large Edentata which were re- 

 vealed by his enterprise. The restricted and rocky area of Attica, as now consti- 

 tuted, could not have afforded sustenance for such a large and varied group of 

 animals, nor could the broken hills and limestone plateaux of Peloponnese have been 

 the haunts of the Hipparions and the Antelopes, if their habits at all resembled those 

 of their descendants living at the present time. From this it follows that Greece 

 was prolonged southwards, in the direction of Africa; and if Africa were then, as 

 now, the headquarters of the antelopes, it is very probable that one of the lines by 

 which they passed over into Europe was in this direction. In the Pliocene age, 

 the presence of the Hippopotamus alike in Italy, France, and Germany can only be 

 accoimted for by the continuity of the African mainland so as to allow of the 

 migration northwards of that animal. It would seem, therefore, that then also the 

 area of the Mediterranean could not have formed the barrier to migration which 

 it does now. But nevertheless the marine strata of Lower Lombardy, of Sicily, 

 and of Marseilles prove that in some districts the present land was submerged 

 during a part of the Pliocene age. 



''iMiat was the physical geogxaphy of the Mediterranean during the Pleistocene age ? 

 The condition of Southern Europe at that time is an important factor in arriving at 

 any true conclusions as to the Pleistocene climate in France, Gennany, or Britfiin ; 

 for if it be proved that a mass of land then extended where the MediteiTanean now 

 rolls, the extension must necessarily have affected the heat of summer and the cold 



