360 MR. J. BESWICK PERRIN ON THE 
the base of the 1st phalanx of the 2nd digit; the ulnar one, into the middle of the 
ulnar side of the 2nd metacarpal. 
The extensor brevis digitorum (interosseous) is situated in the interval between the 
2nd and 3rd metacarpals. It is inserted into the base of the 2nd phalanx of the 2nd 
digit, and to the ulnar side of the preceding tendons. In the latter respect it resembles 
the extensor indicis more than the muscle which I have already described under that 
name. 
The supinator brevis and anconeus present their usual arrangements, as also the 
remainder small muscles of the manus. 
Caudal Muscles. 
These are well developed, and may be divided into three classes—dorsal, ventral, 
and lateral. The dorsal muscles are two in number, the levatores caudz superficialis 
and profundus. 
The levator caude superficialis is attached by its proximal end to a deep depression 
external to the posterior median sacral ridge by tendinous fibres; distally, to the spines 
of the caudal vertebre by aponeurotic fibres, which seem to decussate across the median 
line. 
The levator caude profundus is situated on a deeper plane than the preceding, and is 
partially overlapped by it. It springs from the distal dorsal extremity and excavated 
surface of the ischium, and also from the lateral aspects of the caudal vertebre. It is 
inserted into the fascia covering the bases of the three or four inner feathers of the tail, 
partly into the superior surface of the caudal gland, and also into the extremity of the 
median spine of the caudal vertebra. 
The lateral muscles are three in number :— 
1. Abductor caude externus. 
2. $5 » anterior. 
3. = » posterior (quadratus coccygeus). 
Abductor caude externus (pubo-coccygeus) arises from the posterior extremity of the 
os pubis. It is inserted into the bases of the one or two outer tail-feathers. 
Abductor caude anterior.—This is a large and extensive muscle. Its lateral edge 
only, however, can be seen in the figure. It arises from the tuberosity of the ischium, 
from the apex of the transverse processes of the coccyx, occupying the lateral free aspect 
of the tail. It is inserted into the base of the outer aspect of the fifth tail-feather. 
Situated upon the bases of the tail-feathers is a large triangular-shaped rump-gland. 
The Ventral Muscles of the Tait. 
These are :— 1. The depressor caude superficialis. 
2. The depressor caude profundus. 
3. Dilator caude rectricum. 
