J. Playfair MeMurrich 181 
diminution in the amount of the oblique musculature in the middle 
layer, as well as a tendency for it to associate itself more or less closely 
with the superficial layer. 
Taking the condition found in Phrynosoma cornutum as typical, 
the arrangement of the muscles at about the middle of the forearm is 
as shown in Fig. 2. Starting from the ulnar side there is first the 
flexor carpi ulnaris (F. C. U. and F. C. U.’), consisting of two distinct 
slips; traced distally these fuse to form a single tendon which inserts 
into the ulnar side of the carpus, while proximally they separate more 
Fic. 2. Transverse section through the middle of the forearm of Phrynosoma cor- 
nutum. F. C. R., flexor carpi radialis; F.C. U. and F. C. U’., lateral and medial 
portions of the flexor carpi ulnaris; PP II, III, deep portions of the palmaris com- 
munis; PQ, pronator quadratus; PS, superficial portions of the palmaris communis ; 
P.T., pronator teres; R, radius; rp, ramus profundus; rsm, ramus superficialis me- 
dialis; sw, ramus superficialis ulnaris; U, ulna. 
and more, their origins from the internal condyle being separated by 
the epitrochleo-anconeus, whose insertion into the ulna hes above the 
level of the section figured. 
The median portion of the arm is occupied by a strong mass which 
forms the flexor digitorum profundus (auct.), although it would be 
better to use the term flexor communis digitorum employed by Stan- 
nius, or, better still, palmaris communis if we are to regard it as a 
single muscle. In reality it consists of five distinct portions, only four 
of which are seen in Fig. 2. Two of these four (P. 8.) are superficial, 
