416 Scientific Intelligence. 



with 19 lithographic plates. — This volume is the concluding part of the 



Journal. It contains an account of the Fossil botany of the Permian, 

 illustrated by 



many, Russia and other parts of Europe, and Great Britain. An Appen- 

 dix includes an Index Plantarum and a long table showing the geolo- 

 gical and geographical distributicn of the Permian in Europe. This 

 work of Dr. Geinitz should be in the hands of all who would understand 

 the Geology of the Permian period, — a period having a special interest 

 from its relations to both the Palaeozoic and Mesozoic eras. While es- 

 sentially belonging with the former, it is the transition period between 

 the two. The recent discovery of Permian beds west of the Mississippi 

 renders the work of additional interest to American geologists. 



3. On the footprints of Limulus as compared tvith the Frotichnites of 

 the Potsdam Sandstone ; by J. W. Dawson, (Canadian Naturalist).— In 

 this paper Mr. Dawson compares the impressions called Frotichnites (see 

 Jour. Geol. Soc. London, vol. viii) with the tracks of a modern Liroulus, 

 illustrating the subject with figures. The following are his conclusions 

 with regard to these Potsdam impressions: — 



"(1.) The conjecture of Owen that they may have been made by a 

 creature somewhat resembling Limulus, is verified by the impressions 



'^\2.) Tl 

 depended 



group mignt maicate specitic diversity, is also vmdicatea oy iu« '«^'"' 

 with this limitation, anticipated by Prof. Owen, that tracks like F. lineatus, 

 might have been made by any of the animals which made the other im- 

 pressions, and that if like Limulus they possessed one large pair of feet 

 making the principal marks, and smaller ones occasionally used, the num- 

 bers of marks may have somewhat differed in ditferent circumstances. 

 Still it is evident that a species of Limulus having a difierent number ot 

 divisions of the posterior toes, from that to which these remarks relate, 

 might be distinguished by its footprints. 



(3.) The animal or animals producing the Protichnites probably re- 

 sembled Limulus in general form, and in the possession of a strong cau- 

 dal spine. They probably diflfered from Limulus in the less breadtti or 

 depth of the cephalo-thorax, and in the greater complexity and compara- 



(4.) Some at least of the Protichnites were probably produced by 

 animals creeping on wet sand ; but F. lineatus and the Climactichmtes,^^ 

 the work of a similar animal, were formed under water. This accc»rds 

 with the view entertained by Sir W. E. Logan as to the conditions ot de- 

 position of the Potsdam sandstone ; and it is probable that these ancieni 

 Crustaceans, like the modern Limulus, frequented the sandy beach to 

 the purpose of spawning, and may sometimes have been left dry by 



(5.) The suppositions above stated would account for the absence or 

 rarity of remains of the animals which produced the Protichnites. i 

 rare to find on the modern beach any fragment of an adult Lunula*' 



lie further view of Owen that the grouping of 1 

 on raultifid limbs, and that the number of impressions in a 

 specific diversity, is also vindicated by the facts, 



