Revieivs — Dr. James GeiMe's Great Ice Age, 29 



distinctive external feature by wliicb Salmonoids can be separated 

 from Clupeoids. The nature of the matrix would not admit of the 

 preservation of an adipose dorsal fin, even if it were originally 

 well developed. Three osteological characters of Osmeroides and 

 Aulolepis, however, now made known for the first time, combine to 

 suggest comparisons only in one direction, namely, w^ith the modern 

 genera Elops, Megalojys, and their extinct allies. These characters 

 are (i.) the union of the parietal bones mesially to the exclusion of 

 the supraoccipital from the cranial roof; (ii.) the arched maxilla 

 overlapped above by two larger supramaxillary bones ; and (iii.) the 

 presence of a large gular plate. It is true that although in the 

 typical Salmonidge the supraoccipital separates the parietals on 

 the cranial roof, there are rare instances (e.g. Thymallus) in which 

 the parietals are in contact throughout their length. Further, it is 

 known that the double supramaxilla is not quite constant in the 

 Clupeoides, Elopines, and their allies. It may also be argued that 

 as Dr. Giinther admits to the Clupidge living fishes with a gular 

 plate (Elops, Megalops), there is no reason for excluding from the 

 Salmonidse any primitive fishes which differ only from the living 

 members of this family in the possession of such a plate. Never- 

 theless, so far as the present writer is aware, supramaxillaries of the 

 form described above in Osmeroides and Aulolepis have not hitherto 

 been observed in any Salmonoid, while they are the most common 

 feature among Clupeoids and Elopines. The two Cretaceous genera 

 under discussion may therefore be provisionally associated with the 

 latter. The fishes named Osmeroides from the Chalk of Mount 

 Lebanon may also be placed here, for they likewise exhibit a large 

 gular plate; and Elopopsis is already assigned to the same systematic 

 position by common consent. Elops and Megalops, indeed, have 

 many more close allies in Cretaceous and early Tertiary strata than 

 has hitherto been suspected, and the type they represent seems to 

 have been dominant among the earliest Physostomi. 



12, IB "V I E -W S. 



I. — The Great Ice Age and its Eelation to the Antiquity 

 OF Man. By James Geikie, LL.D., D.C.L., F.RS., etc. Third 

 Edition, largely re-written. 8vo, pp. xxviii. and 850; Maps 

 and Charts xviii. ; Woodcuts 78, and Frontispiece. (London : 

 Edward Stanford, 1894.) 



THE long interval of seventeen years which has elapsed since the 

 second edition of this work was published, must not be taken 

 as an index that the subject of the " Great Ice Age " has during 

 this period lost its interest with geologists or with the public 

 generally, for the number of workers in this branch of geological 

 investigation, and the amount of literature on it which is constantly 

 appearing, seem to be alike on the increase, though not, perhaps, of 

 late years so markedly in this country as in Germany and in the 

 United States. Eeaders of this Magazine are well aware of the 

 persistent frequency with which glacial subjects are brought forward 



