MYOLOGY OF THE CHEIROPTERA. 
145 
three fourths ; in the glenoid the tendon is half the length of the arm and the belly half. 
Except in Eleutherura and Cephalotes the bursa beneath the long tendon does not open 
into the shoulder-joint. Professor Humphry describes it correctly in Pteropus as lying in 
a separate bursal canal and being separate to its insertion. Professor Aeby says that 
in the common Bat the two heads are perfectly fused together (Siebold & Kolliker’s 
Zeitschrift, x. p. 45). According to this author the biceps is to the brachialis anticus 
in weight as oO'To : 1-40. 
The brachialis anticus is a very small muscle, so small in Macroglossus as to be 
scarcely detectable ; it arises from the external side of the humerus, in front of and above 
the musculo-spiral nerve and external to the biceps; it passes posterior to that muscle 
to be inserted into the ulna. A bursa separates its tendon from that of the biceps. 
Meckel describes this muscle as long and slender. In Plecotus and the others of the 
Yespertilionidse it arises from the upper point of trisection of the humerus, and seems 
like a single thread of muscular fibre. Professor Humphry speaks of it as arising from 
the inner side of the humerus just beneath the insertion of the coraco-brachialis, an 
arrangement which I did not see in any of my specimens of Pteropine Bats ; in them 
its origin is anterior, and in P. edulis, though inclining slightly to the inner side, yet still 
on a plane, is inclined to the coraco-brachialis. This muscle is largest proportionally in 
the Eleutherura marginata ; it is also large in Cephalotes , and arises from the front of 
the humerus, commencing below the pectoral ridge but not near the coraco-brachialis ; 
its insertion is behind the long head of the biceps. Professor Humphry found in the 
female Pteropus a band of this muscle going into the biceps, which I did not see in any 
of my specimens. In Cynonycteris it was exceedingly feeble. 
Triceps longus in Plecotus arises as usual from the tricipital subglenoid ridge ; it has 
a single thick upper belly and a long tendon, which is separate from the tendon of the 
rest of the muscle until near its insertion; it is overlain by a thin dorsi-epitrochlear 
expansion, more areolar than muscular in structure, but which comes off from the 
tendon of the latissimus dorsi. In the other Vespertilionine Bats the long head is 
double, composed of two perfectly distinct muscles, one of which arises a little above the 
other. In Vampyrops there are also two scapular heads, which very soon coalesce. In 
Artibeus jamaicensis there are two similar long heads, but they do not unite so high up. 
In Macroglossus the origin is single, wide, with no trace of a dorsi epitrochlearis, and 
coalesces with the humeral heads before its insertion ; it is similar in Cephalotes, but in 
Megciderma it is distinctly double, the external being large with a tendinous origin, the 
internal being tendinous and fleshy ; they are quite separate to the lowest fifth ; no trace 
of a dorsi epitrochlear exists in this species. Meckel says that the triceps in the Bat 
has three heads of the same length ; one of these is scapular, two are humeral, arising 
from the upper part of that bone, while a fourth head arises from the back of the 
humerus lower down. In Pteropus Professor Humphry describes finding some fibres 
from the acromion deltoid passing into this muscle ; but this arrangement I have failed 
to find in any species, although in Eleutherura and Pteropus they are closely applied. 
