1905. ] OSTEOLOGY OF THE EURYLEMID#. DD 
In the Eurylemidz and Cotingide—at least in so far as 
Rupicola is concerned—the major portion is well developed, but 
the brevis portion has now receded, not extending beyond the 
middle of the humerus, and having an entirely fleshy insertion ; 
the longus portion, on the other hand, is slender and terminates 
in a long tendon. 
This interpretation of the transformations of the deltoides 
major et minor, it will be noticed, runs directly counter to that of 
Dr. Chalmers Mitchell, who, in a paper “On the Anatomy of 
Gruiform Birds” (6), contended that apocentricity in this muscle 
was shown by the gradual extension down the shaft of the major 
portion. It would seem, rather, as if the archicentric condition 
were represented by the maximum downward extension, and that 
apocentricity is represented by the gradual reduction of muscular 
tissue. 
That this reduction and inevitable suppression of the brevis 
portion represents an extremely specialised condition there can be 
no doubt; and the fact that it is shared also by the Cotingidee 
seems to me, coupled with the numerous other points which these 
two groups share in common, to show conclusively that the 
EKurylemide and Cotingide must henceforth be regarded as very 
closely related forms. 
These two groups differ in some other myological characters, as 
might be expected. The most noticeable is the fact that the 
latissimus dorsi posterior in the Cotingide appears to be wanting, 
though it must be remarked J have only been able to examine a 
single specimen of Rupicola in this connection. In the Euryle- 
mide both muscles are present, strap-shaped in form, and widely 
separated ; therein differing from the Corvide, in which they are 
of considerable size and shghtly overlap one another. But this 
feature is one of many primitive characters which the Corvide 
have retained. 
The peculiar myological resemblances which these birds share 
do not necessarily imply relationship ; but, as I have just remarked, 
there are so many structures in which these two groups agree, 
that it is impossible to entertain any notion of convergent 
resemblance between the two. The poimts of likeness are so 
peculiar, and affect such different, independent systems, that 
correlated variation and convergence cannot be regarded as a 
satisfactory explanation of the case. When two apparently con- 
vergent forms come to be particularised, each new point of 
resemblance which is brought to light is to be regarded as an 
additional link in the chain of evidence, establishing the common 
origin of the two forms in question. 
Thus, then, I contend there is no evidence which will justify 
the present isolated position which has been almost universally 
assigned to this group during the last few years. It is quite 
possible that further investigation will show that the Eurylemide 
are entitled to rank no higher than a subfamily of the Cotingide. 
