244 Prof. Huxley on Archseopteryx lithographica. [Jan. 30, 



the following remarks, which are, in part, intended to rectify certain errors 

 which appear to me to be contained in the description of the fossil in the 

 Philosophical Transactions for 18G3*. 



It is obviously impossible to compare the bones of one animal satisfacto- 

 rily with those of another, unless it is clearly settled that such is the dorsal 

 and such the ventral aspect of a vertebra, aad that such a bone of the limb- 

 arches, or limbs, belongs to the left, and such another to the right side. 



Identical animals may seem to be quite different, if the bones of the 

 same limbs are compared under the impression that they belong to oppo- 

 site sides ; and very different bones may appear to be similar, if those of op - 

 posite sides are placed in juxtaposition. 



The following citations, and the remarks with which I accompany'them, 

 however, will show that these indispensable conditions of comparison have 

 not been complied with in the memoir to which I refer. 



1 . " The moiety (Plate I.) containing the greater number of the petrified 

 bones exhibits such proportion of the skeleton from the inferior or ventral 

 aspect" (I. c. p. 34). 



I propose to show, on the contrary, that the fossilized animal presents, 

 in general, its dorsal aspect to the eye, though one of the most conspicuous 

 bones may have been so twisted round as to exhibit its ventral face. 



2. The demonstration that the bones of the Archceopteryx are thus 

 wrongly interpreted, may be best commenced by showing that what is 

 called right femur (65), tibia (66), and bones of the foot (68, i, ii, Hi, iv),'* 

 I. c. p. 35, are respectively the left femur, left tibia, and bones of the 

 left foot. 



That such is the case is very easily proved by the circumstance that (as 

 is very properly pointed out in the memoir) the second toe of the foot in 

 question is that which lies uppermost, while the plantar surface of the 

 foot is turned outwards, and its dorsal aspect towards the vertebral column. 



If the limb in question were, as the describer of the fossil supposes, the 

 right leg, it would obviously be impossible to place the foot in its present 

 position, imless the numbers of the phalanges in its toes were the reverse of 

 what is observed in Birds ; that is to say, the uppermost toe, that which 

 has three phalanges, must also be the outermost. Nevertheless the de- 

 scriber of the fossil justly lays great stress upon the fact that the toes have 

 the same number of phalanges as in birds. As a matter of fact, this is 

 quite true ; but it would not be true if we were to assume with him that 

 the limb in question is the right leg. 



3. Certain parts of the fossil which lie upon the opposite side of the 

 spine to the so-called right leg" are named, at p. 34 of the memoir 

 cited, " Portion of the left os innominatum, showing part of the ihum (62) 

 and ischium (63), with the acetabulum («)." 



^- " On the Arcli(so}jteryx of Von Meyer, -with a description of the Fossil Remains of a 

 Long-tailed Species, from the lithographic stone of Solenhofen." By Professor Owen, 



