1893. J Clavicular Avcli in IcJitlniosauria and Sauropterygia. 159 



('" 

 -cor., right coracoid ; Sc., right scapula, visceral and internal aspects j 

 f, portion of the scapulo-coracoid foramen. (After von Meyer.) 



Sanropterjgia ; but since 1882 it has been clear to me that they form 

 a different order, which is intermediate between the Sauropterygia 

 and the Anomodontia. And although it may not be possible at 

 present to fully establish this conclusion, it is one in support of 

 which evidence can be adduced. It is on this account that the 

 interpretation of the shoulder girdle in Nothosaurus has appeared 

 to me to have a two-fold significance as establishing, first, by 

 comparison with Plesiosaurus, the true nature of the clavicles of 

 Sauropterygia, and secondly, by comparison with the Anomodontia, 

 I think it places beyond question the true nature of the precoracoid. 

 The large questions of organic affinity I regard as safe bases for the 

 morphological interpretation of the skeleton. If I do not enter into 

 discussion of Lariosaurus, it is because the scapulae are displaced, and 

 I have already referred to the type on a former occasion. 



The Anomodont comparison is important. First there is a notoh 

 in the Anomodont scapula which I regard as a Mammalian character, 

 and this notch is completed externally by the ossified precoracoid, 

 and passes obliquely through that bone, so as to excavate the 

 coracoid. The relations of these bones are shown in Pareiasaurus 

 Baini (fig. 2), and in many South African Anomodonts. As the 

 specimens have been figured, it may be sufficient to refer to the 

 figures as showing that the relations of the precoracoid to the 

 coracoid and scapula are almost identical with those which I have 

 suggested for the cartilaginous precoracoid in Nothosaurus (fig. 6) 

 and Ichthyosaurus (figs. 1 and 4). Mr. Hulke has not pointed 

 out any difference in this part of the skeleton from the Ichthyo- 

 saurian or Nothosaurian type, which would invalidate my interpre- 

 tation that the difference between them, which is most essential 

 in plan, is that Anomodonts have the precoracoid ossified. The 

 ossitication occupies substantially the same position which I have 

 attributed to the precoracoid in the types in which it is supposed to 



