Prof. Huxley on. Archaiopteiyx lithograpliica. 221 



poses, the right leg, it would obviously be impossible to place the 

 foot in its present position, unless 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 describer 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 inuominatum, showing part of 

 the ilium (62) and ischium (63), with the acetabulum («)." 



A full description of this mass of bone as " the left os inuomina- 

 tum, including the anterior two-thirds of the ilium, and the anterior 

 half, or more, of the coalesced ischium," is given at p. 39 ; and at 

 p. 40 I find, "The inferior or central* face [of the sacrum], as in 

 the case of the slightly dislocated left innominatum, is towards the 

 observer." 



There is no doubt on any side, that the end of the bone in question 

 which at present is directed forwards is its true anterior end, and 

 that the edge which is turned towards the spinal column is the true 

 dorsal edge. The question is, whether the face of the bone which is 

 exposed is its outer (or dorsal) or its inner (or ventral) face. In the 

 former case it must needs be a right ilium, in the latter a left 

 ilium. 



That it is the outer face of the bone which lies uppermost appears 

 to me to be demonstrated — 



(a) By the fact that the iliac margin of the acetabulum is promi- 

 nent, and that the adjacent surface of this ilium rises to this margin. 

 I am not aware that any vertebrate animal exists in which the ace- 

 tabulum lies at the bottom of a funnel-shaped depression, such as 

 would be the case in Archceopteryx if the bone in dispute were the 

 left OS innominatum seen from the inner side. 



(6) By the fact that a small portion of what appears to be an inno- 

 minate bone can be descried in close relation with the proximal end 

 of what has just been shown to be the left femur ; while the right 

 femur (called left in the memoir), though dislocated, is not very far 

 from the bone under discussion. 



(c) By the further consideration, that if this were not the right 

 OS innominatum, it would be as curiously unlike the corresponding 

 bone of a bird in the form of its surface as it resembles it in all other 

 respects. 



4. The bone marked 51' is named "left scapula" (I. c. p. 34), 

 and that marked 51 "right scapula" (/. c. p. 35); and a full de- 

 scription of these bones, as such, is given at pp. 36 and 37 of the 

 memoir cited. 



* " Central " in the original. The word appears to have been substituted 

 by an error of the press for " ventral." 



Ann.d'Mar/.N.Risf. Ser. 4. TW. i. 16 



