162 DR. P. CHALMERS MITCHELL ON THE [| May 16, 
large tendon inserted to the radius (R.) and a very small tendon 
to the ulna (U.). There is also a second belly, smaller and rounder, 
arising almost wholly from the coracoid tendon of origin (BI.2), and 
towards the lower end of the humerus passing into a round tendon 
which is inserted to the ulna only (U.), distal to the insertion 
of the ulnar branch of the tendinous fork of Biceps 1. This 
doubled condition of the biceps is practically repeated in Scolopax, 
except that Bi. 1 appears to supply only the tendon to the radius, 
and the same state of affairs is present in Gallinago, Charadrius, 
Himantopus, Vanellus, and Rhynchea. It occurs also in Glareola 
and in Thinocorus, but in the latter the humeral head is 
degenerate although present. 
This complication of the biceps shows a link between the 
Charadriidee, through Chionis, with a more exaggerated peculiarity 
in some of the Gulls. The condition in Scolopax differs from that 
in Chionis practically only in the tendon of Bi. 1 in the latter 
being forked so as to be inserted both to the radius and ulna. If 
we suppose this fork in Chionis to be split up into the body of the 
muscle so as to separate the portion of the belly arising from the 
acrocoracoid tendon from the portion coming from the humerus, 
the Gull condition would be reached. In Larus, for instance, the 
tendon of origin arising from the acrocoracoid divides into two 
fleshy bellies, the one representing Bi. 2 in text-fig. and running 
to the ulna, the other, fused with Bi. 1 in the figure, running 
independently to the radius. As there is very strong evidence of 
other kinds for supposing that the Gulls are modified from a 
Gharadriiform stock, it would seem natural to suppose that here 
we have to deal with a case of progressive complexity, starting 
from the Scolopax condition and leading through Chionis to the 
Gull condition. But it is important to remember that, in cases 
of muscles and tendons of birds, the general morphological course 
is from the more complex to the simpler, and, to my mind, it is 
more probable that the Scolopax and general Limicoline condition 
is a simplification from the Gull condition, Chionts showing how 
the simplification may have come about. 
Deltoidis patagialis—This muscle is of moderate width in all 
these birds, and gives off the longus and brevis tendons from its 
relatively broad distal extremity, with not more than the slightest 
indication of division into peaks for the different tendons, and so 
far remaining in a primitive or archecentric condition. With 
regard to the tendons, Wdicnemus displays a condition markedly 
different from that found in all the others. The longus tendon is 
simple and slender ; it has an anchor to the humerus, and, after 
being joined by the biceps slip, gives off one or two very weak 
slips of fascia to the patagium, and then takes the usual course 
towards the wrist. The brevis tendon is simple, flat, and well 
marked ; it runs an undivided course towards the elbow, parallel 
with the biceps, and, close to its insertion, broadens out into a 
fan-shaped termination, which displays in a reduced condition the 
three slips named respectively a, 8, y by Firbringer. In all the 
