166 DR. P. CHALMERS MITCHELL ON THE [May 16, 
inserted to the femur along a narrow vertical line. In Vanellus 
the caudal portion is very large, whilst the accessory portion 1s 
present, but minute and with a tendinous degeneration similar 
to that just described. In Thinocorus, Hydrophasianus, and 
Rhynchea both portions are present and large. In Glareola, 
Charadrius, and Himantopus the caudal portion is large, and the 
iliac is extremely minute, represented by not more than a few 
fibres. In Gallinago and Scolopaxc the caudal portion is of 
moderate size, the iliac portion completely absent. 
Text-fig. 28. 
IL.FIB (1) 
NK 
Wes fits Z. 
Wizz 
Vp 
UY 
1 
CAUD ILL, 
TRAE. 
FT. 6. 
11 FIB (2) 
Thigh-muscles of Chionis alba. Right thigh, external view. 
IL.TR.E., P., M., A. Tlio-trochanterici externus, pesterior, medius et anterior. 
IL.FIB. (1). Origin of ilio-fibularis seu biceps, cut and reflected. IL.FIB. (2). 
Insertion of biceps, cut and reflected. I.F. Ischio-femoralis, seu obdurator 
externus. CAUD.IL.F. 1,2. Insertions of caud-ilio-femoralis (accessory femoro- 
caudal (1) and femoro-caudal (2)). CAUD.IL.FL. Caud-ilio-flexorius, cut, and 
origin reflected. IS.FL. Ischio-flexorius. P.I.F. Pub-ischio-femorales, seu 
adductores longus et magnus. The tendinous areas are dotted. X. Tendinous 
area on accessory femoro-caudal. F.T.E. Femoro-tibialis externus. 
(dicnemus in this respect, as in others, shows its wide diver- 
gence from the typical Limicoline condition. Of the others, 
Thinocorus, Hydrophasianus, and Rhynchea show what is probably 
the archecentric or generalised condition for birds, the presence 
of both muscles in a well-marked form. The remaining birds of 
the list show that the tendency of modification in the group is for 
the disappearance of the iliac portion (the ‘‘accessory ” of Garrod) ; 
and complete disappearance has been reached by Gallinago 
and Scolopax, two birds in other respects relatively highly 
specialised. 
Caud-ilio-flexorius (Semitendinosus and Accessory semitendi- 
nosus), Ischio-exorius (text-fig. 28).—In all these birds the three 
