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Show 168 ON THE ANATOMY OF LIMICOLINE BIRDS. [May 16, side for digits 2 and 4 respectively, except in Glareola and Thinocorus, where it is a fan-shaped slip of fascife common to the three digits, with the slightest trace of specialisation into tendons on the edges of the fan. Peroneus superficial/is (with slip to perforated tendon of digit 3), Peroneus profundus.-These muscles are present, with one exception, in the normal or archecentric condition in all the birds on the list. The exception is the peroneus profundus in CEdicnemus, in which bird it is practically absent, the absence being another point in which CEdicnemus differs from the Limicolfe and recalls many of the Gruiformes, such as Otis. Flexores perforantes et perforati.-These muscles and tendons, including the slip connecting the tendon of digit 3 with the corresponding tendon of the perforated flexor, all present a practically identical condition, which does not differ in any important respect from the condition in the majority of the Gruiformes. Flexores perforati.-These muscles in all the birds on my list have the usual inter-relations and divide into tendons for the three digits in customary fashion. The muscular mass has three heads : of these I have already described the ambiens head, which is similar throughout, except that there is no accessory ligament from the head of the fibula in Chionis. The external head is fleshy in Himantopus ; it is small and tendinous in Chionis, Glareola, Thinocorus, Hydrophasianus, Charadrius, Rhynchcea, and Gallinago. It is absent in CEdicnemus and Scolopax. Flexor prof undus and Flexor longus hallucis.-In my communication on the Gruiform birds I described various ways in which the tendons of these two muscles (which are similar in their origin in all the birds on my list) are united with one another and distributed to the toes. I suggested that probably the most primitive condition was such as is to be found in Eurypyga (7, text-fig. 85, VII), where the longus hallucis sends a slip to the hallux, and distad of this blends so completely with the profundus tendon that each tendon supplies each of the three digits. The condition in Chionis resembles this closely, except that, as in Rhinochetus, the hallucis tendon, after giving ofi' its slip to the toe, is not so markedly spread out for the other toes. CEdicnemus shows a state practically identical with that of Otis; there is no great toe, and therefore no slip to i t ; the spreading out of the junction of the hallucis tendon with the profundus tendon has become obliterated. In Hydrophasianus the condition is exactly as in Eurypyga, except that, although there is a long great toe, there is no slip to it. In Rhynchcea the condition is also the primitive one, except that the slip to the great toe comes off1 a considerable distance above the brandling of the conjoined main tendons for the three other digits. In Scolopax the condition is similar to that in Rhynchcea, but although there is a small great toe there is no slip to it, and the long junction of the two tendons is ossified. |
