ON LEPTOSOMA DISCOLOR. 155 



Myology, fyc. The first pectoral is big ; the second extends at least 

 halfway down the sternum ; the third is not represented. There is no 

 biceps-slip to the patagium,^as is the case in all " Anomalogonatse " except 

 the Caprimulgidae. In none of these points does Leptosoma differ from 

 the Coraciidae or Cuculidoe. The expansor secundariorum is present and 

 well developed ; its proximal end is T-shaped (" ciconiiform" Garrod), 

 the sternal part of the tendon being attached to that bone at the junction 

 of the costal process with the body near the coracoid groove ; it therefore 

 resembles the same muscle in the Coraciidae. In no other birds amongst P. Z. S. 1880, 

 the Anomalogonatae is this muscle present. In the Cuculidse this muscle p ' ' 

 is present, but its terminal tendon is not T-shaped, the sternal moiety 

 being undeveloped. 



The arrangement of the termination of the tensor patagii brevis is re- 

 presented in the accompanying figure (fig. 2, p. 154). 



The main tendon (t.p.br.) runs on to the ulnar side of the arm, and 

 there becomes fused with the fascia covering the muscles. Before doing 

 so, however, it crosses the superficial tendon of origin of the extensor 

 metacarpi radialis longior (e.w.r.), which springs from the humeral tubercle, 

 and becomes firmly blended with it. 



It likewise sends off, distally, a special slip of tendon which joins the 

 same tendon of that muscle more externally (wristward). This is much 

 the same arrangement as in the Coraciidse, as described and figured by 

 Prof. Garrod (P. Z. S. 1876, p. 511, pi. 49. fig. 1), except that in those 

 birds the tendon of the tensor patagii brevis is split into two quite separate 

 halves ; if these were united together, an arrangement would be arrived 

 at practically identical with that of Leptosoma. In the Cuculidae the 

 condition of things is quite different, as in them the " undivided tendon 

 runs on to the ulnar superficial fascia without auy complication " (I. c. 

 p. 512). 



Of the leg-muscles, the glutens primus is present, though small, only 

 slightly overlapping the biceps, and with its fleshy part not reaching the 

 innominate, to which it is attached only by fascia. The ambiens is ab- 

 sent ; the femoro-caudal is very large, but lacks the accessory head, as in 

 all Anomalogonatae. Both the semitendinosus and its accessory are well 

 developed, as is the semimembranosus. The biceps mem, as usual, passes 

 through a tendinous loop. The obturator externus is well developed, and 

 the obturator internus is of a very elongated oval shape. The formula of 

 Leptosoma is therefore . A . X . T, exactly the same as that of the 

 Coraciidae and the greater number of Anomalogonatous birds. In the 

 Cuculidse the ambiens is always present and well developed, and the 

 accessory femoro-caudal usually so *, giving a formula of + . A . (5\ X . T . 



* It is absent only in Cuculus, Chrysococcyx, and Cacomantis. [ Garrod 's MSS.] 



