162 BR. p. CHALMERS MITCHELL OX THE [May 16, 



large tendon inserted to the radivis (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 Gcdlinago, Charadrius, 

 Himantopus, Vanellus, and Rhynchcea. 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 

 Charadriidse, 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 Ghionis to be split up into the body of the 

 mviscle so as to separate the portion of the belly arising from the 

 acrocoracoid tendon fi'om 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 pi/ogressive 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 genei'al 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, Chionis 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 difierent tendons, and so 

 far remaining in a primitive or archecentric condition. With 

 regard to the tendons, CEdicnemus 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 hrevis 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, /3, y by Fiirbringer. In all the 



