MUSCLES OF THE HIND LIMB. 25 
portion becomes trifid distally, and each division sends a tendon to the second, 
third, and forth digits respectively. This tendon bridges the groove of the 
profundus. 
The flexor profundus digitorum (Plate 6, fig. 6, d) arises as in Gymnura and 
Centetes from five heads, and thus differs from that of Potamogale in which but 
three are described. The first of these heads is superficial, from the anterior 
edge of the epitrochlea; its large tendon inserts into the common tendon on the 
radial side at the wrist. This division is more or less distinct throughout its 
distal union with the main mass of the tendon and has been homologized by 
Dobson with the flexor longus pollicis. Two smaller muscles, forming the 
second and third heads, arise in close association from the anterior surface of the 
epitrochlea and the anterior edge of the great sigmoid notch. Their tendons 
become confluent and join the main palmar tendon medially proximal to the 
insertion of the first division. The head of flexor sublimis separates the head of 
the first division from the common origin of the second and third. The fourth 
head arises as a large fleshy muscle along the ectal side of the ulna from the 
olecranon to within about 15 mm. of the distal end of the ulna where its fibers 
merge with those from the fifth division whose origin is from the proximal two 
thirds of the ental border of the radius. These five divisions unite to form a 
thick flat tendon at the wrist. This divides at the base of the metacarpals to 
form the usual five branches, one to the lower surface of each digit. This muscle 
in Solenodon seems most nearly to resemble that of Gymnura in possessing five 
distinct heads. In Centetes the condition is essentially similar, but the closely 
associated second and third heads are united into a single division. In Potamo- 
gale the number of heads seems to be still further reduced. 
MUSCLES OF THE HIND LIMB. 
The psoas magnus (Plate 4, fig. 2, 0) appears to be essentially similar in its 
relations to that of Gymnura, Erinaceus, and Centetes. It arises from the 
transverse processes of the lumbar vertebrae as a thick muscular mass and 
becomes confluent with the iliacus from the ventral side of the anterior ramus of 
theilium. It then tapers to its insertion on the lesser trochanter of the femur. 
The psoas parvus (Plate 4, fig. 2, p) arises as a flat ellipsoidal muscle from the 
ventro-lateral portion of the first lumbar and the anterior portion of the second 
lumbar vertebrae. It then passes posteriorly as a thin flat tendon from 2 to 
3 mm. wide and 30 mm. long to insert on the anterior edge of the pelvis, just 
