8 FOSSIL REPTILIA OF THE 



The monotrematous and batrachian instances show the spinous limb-weapons to be 

 related to sex, and to be present, or fully developed, only in the males. 



In the class of Birds the carpal spurs are common to both sexes, but smaller in the 

 female. 1 



The question remaias — were the radial spines of Iguanodon common to both sexes, or 

 developed only in one, most probably the male ? 



In the Maidstone specimen such appendage, with a concomitant considerable distal 

 expansion of the radius, cannot be discerned. In the best preserved ends of the anti- 

 brachial bones, those, viz., furthest from the humerus (as the separated fragments of the 

 matrix, have been restored in the Maidstone specimen), the closest resemblance traceable 

 to the more complete bones before me is at the proximal ends ; and especially, as originally 

 determined by me, in the ulna, or lower placed bone. In this view the distal ends, espe- 

 cially of the radius, are partly concealed by an overlying vertebra, yet not to the extent to 

 obscure the beginning of the radial expansion if it had existed. The shafts of both radius 

 and ulna seem to be more slender than in Mr. Beckles' Wealden specimen. It may 

 be that this is of a male Iguanodon and the Maidstone specimen of a female one. 



A strange instrument truly in aid of the amorous embrace ; yet, as in the instance of 

 Cystignatlms, and perhaps also the Ornithorhynchus and Echidna, not without a parallel ! 



If the radial spines, on the other hand, were developed in both sexes of the Igua- 

 nodon, and wielded for purposes of defence by the otherwise weaponless herbivore, one 

 cannot fail to discern in them a formidable means of transfixing an enemy — the carnivo- 

 rous Megalosaur, e. y. — in a close death-struggle. 



Mantjs. Plate III. 



With the right and left anti-brachial bones and spinous appendages several bones of 

 both the fore feet were exhumed, but not enough for a complete restoration of either foot. 



They give evidence that the fore-paw was pentadactyle, and that the terminal 

 phalanges, at least of some of the toes, were short, obtuse, rough, serving for the support 

 of horny matter in the shape of a hoof rather than of a claw. Such evidences of the 

 carpal bones as were collected are more or less fragmentary ; and, where a satisfactory 

 union of those belonging to one and the same bone could be made, the homology of but 

 one bone can be safely or with probability be suggested, that, viz., which answers to the 

 large os cuneiforme in the carpus of Lizards. 



The proximal surface of this bone is divided into a convex and concave surface ; the 

 former was apparently adapted to the concavity of the ulnar extension of the distal part of 



1 The Secretary of the Zoological Society, P. L. Sclatee, Esq., F.R.S., kindly informs me that this is 

 the case in the pair (male and female) of the spur-winged geese (Plectropterus) now living in the Society's 

 Gardens. 



