454 P>'of. II. G. Seek// — On the Berlin Archceopteryx. 



at the doubts I have expressed, and which I still entertain, as to 

 the soundness of their speculations. In the interest of geological 

 science, it is desirable, when new and startling theories are pro- 

 pounded, for which public acceptance is claimed, and especially when 

 emanating from quarters entitled to respect, that some one should 

 step forward to weigh the evidence on which these theories rest. 

 Though there are many others who would have discharged this 

 duty much more satisfactorily than myself, still it seemed to me not 

 incompatible with the position I have the honour to hold as 

 President of the Edinburgh Geological Society, to undertake that 

 duty. 



VII. — On some Differences between the London and Berlin 

 Specimens referred to Auchmopteryx. 



By Prof. H. G. Seeley, F.E.S., etc. 



(PLATE XII.) 



IN drawing attention to some characters of the Berlin ArcTicsopteryx, 

 it should be stated that I only know that specimen from a photo- 

 graph taken before the slab was full^"^ developed; and therefore while 

 I believe the following results to be trustworthy as indicating specific 

 and it may be generic differences, it is possible they may hereafter 

 be slightly modified. 



As stated by Vogt, the Berlin slab is ith smaller than the London 

 slab ; assuming the photograph to be of natural size, the following 

 measurements may demonstrate the nature of the relation between' 

 the two specimens. The femur measures in the Berlin slab 4'8 centira. ; 

 in the London slab 6 centim., so that the London specimen is ith 

 longer. The tibia in the Berlin slab measures 6"8 cm. ; in the London 

 slab it is 8 cm. Therefore in the latter the femur is f ths the length 

 of the tibia ; but if this proportion obtained in the Berlin specimen, 

 the femur would have measured 5-1 cm. : hence the second specimen 

 is slightly longer-legged. In the metatarsus the dijfference is nearly 

 ith, for the Berlin animal measures 3 "5 cm., and the London type 

 4-4 cm. The digits of the Berlin specimen measure respectively 

 I'd ; 22 ; 3*1 cms. ; the measurements in the London specimen 

 are 1-7 ; 3-5 ; and 4-5 cms. ; so that the longest digit of the London 

 slab is more than a third longer than the corresponding digit of the 

 Berlin slab. Hence in the latter animal the foot is relatively shorter 

 and the drumstick relatively longer. 



In the fore-limb the Berlin humerus measures 5-9 cm., the London 

 humerus 7 cm.; the difference is between a sixth and a seventh. The 

 Berlin ulna measures 5"1 cm. ; the London ulna 6"7 cm. ; the 

 difference is a little less than a fourth, but while the Berlin humerus 

 is about a seventh longer than the ulna, the London humerus is only 

 about a twenty-third longer than the ulna. This difference is more 

 marked than that between the tibia and femui-, and shows that the 

 fore-arm was relatively longer in the Berlin animal. The difference 

 in the metacarptis is about one-fifth, the Berlin measurement being 

 2-7 cm., the Loudon measurement 3-4 cm. Only two digits can be 



