696 



DR. P. CHALMERS MITCHELL ON THE 



The epicleideal plane of the clavicle passes across the median 

 face of the acrocoracoid and nearly reaches the scapula, with 

 which, however, it is united only by ligament (text-tig. 132, A, CL). 

 Its tip, however, does not extend so far as to cross the acro- 

 coracoid, fand it is therefore wholly concealed when it is viewed 

 from the outer side, the opposite aspect from that shown in text- 

 figure 132. ~Lm Sco2ms the tip of the clavicle projects slightly 

 further. In all the Storks and Herons that I haA^e examined the 

 tip of the clavicle projects completely across the acrocoracoid so 

 that its ligamentous connection with the end of the scapula is 

 freely visible when the shoulder-girdle is viewed from the outside. 



Goracokl. — The basal ends of the coracoid, where they articu- 

 late with the sternum, do not quite meet in Balcenicejys ; they 

 either do not meet, or just meet in Storks ; in Scopus and Herons 

 they overlap. 



The procoracoid process (text-fig. 132, A, Fc.) is very large in 

 Bcdceniceps, with a curved border nearly reaching an emar- 

 gination in the clavicle, with which, however, it is united only 

 by ligament. This process varies in Storks, being almost as 

 large but not expanded in some, small in others (e. g. Tantalus). 

 It is quite small in Scopus (text-fig. 132, B, Pc.) and Herons 

 including Cancroma. 



Pelvis. — Parker lays some stress on the narrowness of the 

 pelvis in Balceniceps, comparing it in this respect with Herons 

 and contrasting it with Storks. Certainly such a difi"ei^ence does 

 exist, but as it was not so striking to my eye as Parker found it, 

 I measured a numljer of pelves of Storks and Herons, reduced 

 the measurements of the narrowest and widest portions of each 

 to a common standard and averaged the results. 



Width of Pelvis in percentage of length. 



Narrowest part. Widest part. 



Pakenice^JS 27 50 



Ardea 25 50 



Cancroma 28 57 



Xenorhynchus ... 35 60 



Tantalus 35 56 



Scopus 37 62 



It will be seen that the width at the widest part differs much 

 less than the width at the narrowest part. In other respects I 

 find that the pelvis of Balcenicejjs is rather more like that of 

 Scopus and Storks than of Herons. There is a well-marked 

 notch separating the distal ends of the ilium and ischium in 

 Balmniceps, Scopus, and Storks which is absent in Herons, in- 

 cluding Cancroma. In Herons, including Cancroma, the dorso- 

 lateral edge of the post-acetabular ilium projects outwards as a 

 sharp horizontal ridge, which is very slightly marked in Scopus 

 and is absent in Balcmiicepis and Storks. 



