12 FOSSIL REPTILIA OF THE 



In no other reptile does the sternum present coracoid articulations so shaped 

 and so placed as in the Pterodactyle. The Crocodilia, in which, as in Pterosauria, 

 the clavicles are wanting, show the broad, sternal margins of the coracoids 

 ligamentarily attached to the middle of the lateral border of the sternum. 



In bats the obtuse, sternal ends of the clavicles are applied to protuberances of 

 the manubrium above the articulations of the first pair of ribs. Only in birds are 

 distinct synovial articular cavities provided for the coracoids, which, in the main, 

 are situated and shaped as in the Pterodactyle. The differences are these: the 

 concavity and the convexity being (as, e. g, in Aptenodytes), the same, the bent 

 grooves so formed are much longer than in the Pterodactyle, with a concomitant 

 greater expansion of the ends of the bones they firmly lodge. The coracoid 

 grooves are divided by a non-articular, median depression in Aptenodytes, but 

 this, in some other birds, is wanting, the coracoid grooves decussating across the 

 middle line, e. g., in the Heron.* There are various minor modifications of the 

 coracoid grooves in the breast-bone of birds. 



The marked distinction in the breast-bone of the Pterodactyle is its com- 

 pression behind the coracoid articulations, and the distinct commencement of the 

 shield-like expansion behind that articular part. 



In most birds the "manubrium" projects from the mid-space between the 

 coracoid gi'ooves, and is distinct from the "keel;" in some it is bifurcate ; in the 

 penguins it is as little developed as in the Pterodactyle, and is as directly 

 continuous or connate with the forward production of the keel. In this 

 production Aptenodytes patachonica most resembles, amongst birds, the 

 Pterodactyle. The parts are homologous, and if we name that production 

 the forepart of the keel of the breast-bone in the aquatic bird, we must apply 

 the same name to it in the Pterodactyle ; only in the latter the keel subsides 

 sooner beneath the expanded part of the sternum. 



In the Crocodilia the broad, thin, sternal borders of the coracoids are attached 

 by fibrous substance to the fibro-cartilaginous, or, in old animals, partially 



Es besitzen aber auch die Maulwiirfe am brustbein diesen Kiel, der daher nicht unbedingt als em Zeichen 

 des Flugvermogens gelten kann ; er setzt eigentlicb nur starke Brustmuskeln voraus, die daran befestigt 

 waren. Selbst in den Schwirumvb'gelu die nicht zu fliegen vermogen ist der Kiel vorhanden fur starke 



Brustmuskeln, die hier zum Schwiramen eben so nothig sind wie dem Maulwiirf zum Graben 



Aus diesen Betrachtungen ergiebt sicb, dass der Pterodactylus nacb der Bescbaffenheit seines Brustbeins 

 weder ein eigentlicbes Wasserthier, noch ein Graber war, vielmehr ein Thier der Luft." (' Beptilien aus 

 dem Lithographischen Schiefer, ' &c, fob, p. 17.) 



Professor Quenstedt, however, seems to me to have rightly appreciated the homology of the forepart of 

 the sternum and the physiological deductions from it : " Der Kamm sprijjgt vorn einen halben Zoll weit 

 iiber die Flache des Knochens binaus, gibt daher Beweis genug, das das Thier fliegen konnte." (Op. cit., 

 p. 44.) 



* 'History of British Fossil Mammals and Birds,' 8vo, 1846, p. 556, fig. 236. 



