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Show 430 MR. F. E. BEDDARD ON THE [June 3, convinced that myology is a most valuable aid in determining the affinities of different genera, and even groups, of birds, its use in my opinion is restricted to this; no wider inferences can be drawn with any degree of safety. The semimembranosus arises deep of the semitendinosus, from the ischium ; it is a tolerably strong muscle, though slighter than the semitendinosus; it is inserted by a broad flat tendon considerably below the insertion of the semitendinosus on to the tibia. The relative positions of the insertions of this muscle and of the semitendinosus are shown in the drawing (Plate X X X I X . fig. 3; and more in detail in fig. 3 a). As Garrod [2] has pointed out, this muscle is usually very thin in the Grebes and may even *, as stated by Sundevall, occasionally disappear. I find, however, in some notes left by Prof. Garrod that Colymbus glacialis has a large semimembranosus " twice the size of semitendinosus." Its origin appears to be a little peculiar ; it arises from the ilium and ischium near to the posterior end of the pelvis. The femoro-caudal, is a strong and well-developed muscle which has the usual origin and ends by a narrow thin tendon of insertion. The accessory femoro-caudal is a short fleshy muscle which is inserted in common with the femoro-caudal (as shown in Plate X X X I X. fig. 3); it appears as if inserted on to the tendon of the latter. The adductor muscles appeared to me to be comparatively small in size ; the lower of the two was largely tendinous. The gastrocnemius arises by three heads: the outer head is a large fleshy muscle arising by a thin and strong tendon from the femur, and also by a few muscular fibres from the fascia covering the leg, which has already been spoken of in connection with the biceps; the inner head is of equal size and arises from the cnemial crest of tibia, from fasciae covering the leg, from septum between itself and the peroneus longus ; its tendou joins that of the outer head at the tendo Achillis. The middle head is a very tiny muscle with a very long tendon of insertion ; it unites with that of the inner head before the latter joins the tendon of the outer head of the gastrocnemius. There are two peronei muscles which have the usual relations; the tendon of the longus fuses with the tendon of the superficial flexor of the third digit. The peroneus brevis is a large muscle which forms a kind of sheath round the tibialis anticus and the other muscles which spring from the front of the leg; its flat, rather broad tendon, appears to be inserted on to the heel in the usual fashion. The tibialis anticus has the usual two heads, one femoral, the other tibial; its tendon just before its insertion into metatarsus gives off a small branch to the fascia which covers over the tendon of extensor communis. According to Giebel's [6] notes upon the myology oi Heliornis surinamensis, the pectoralis primus and secundus agree with the same muscles in Podica; he mentions also the large " musculus gracilis" ( = ambiens). The peroneus longus has evidently the same relations, and is, as in Podica, a large muscle. The description of 1 Garrod, M S . (in Podiceps minor). |
