ANATOMY OF THE LEMUROIDEA. 69 
muscles, named by Burmeister, the one vastus externus (his no. 17), and the other 
cruralis (his no. 19)'. 
These two muscles are again separable, according to him, into a superior and inferior 
layer, as is also the case with regard to the vastus internus, as Burmeister says that 
the exterior muscles are divisible into two distinct layers, making in all seven exterior 
muscles of the thigh. ‘The first layer consists, besides the rectus femoris, of the vastus 
externus, the vastus internus, and the cruralis; the second layer of the so-called deep 
vastus externus, deep vastus internus, and deep cruralis. 
Of these seven muscles as many as two (namely, the cruralis and the superficial 
vastus externus) correspond to our vastus externus of Z. catta. Burmeister’s deep 
cruralis is our crureus; his deep vastus internus has no representative in the Lemuroids 
examined by us, unless, as we think, it is a separable inner part of our crureus, and his 
deep vastus externus a similar external portion of the same. 
Crurevs.—This is a very distinct and separate muscle, extending along the whole 
length of the femur. It is narrow and somewhat compressed at its upper part, and 
arises from the whole of the front and middle of the outer side of the femur as high as 
its neck, extending round that bone from the insertion of the gluteus maximus on one 
side to that of the adductor magnus on the other. It has a broadly tendinous glistening 
surface, and is inserted as usual. 
In ZL. varius there can hardly be said to be a subcrureus present; but the crureus 
muscle itself descends on either side of the condyles, while the main tendon passes on 
to the patella. The muscle is figured in this species by Cuvier, /. ¢. pl. 70. fig. 2, 0. 
In L. nigrifrons we found a distinct subcrureus muscle; this lies beneath the lower 
tendinous part of the crureus, and it covers almost the lower half of the shaft of the 
bone. It is most muscular on the outside. 
In Galago crassicaudatus (Pl. V. figs. 19 & 20, and Pl. VI. fig. 25, Cr.), as in other 
species of the genus examined, the crureus is much as in L. catta, the fibres reaching 
very far round, but not quite to the linea aspera. 
In Nycticebus tardigradus the crureus presents the same characters as in L. catta. 
In Tarsius? this muscle is described as the cruralis inferior (no. 16@) (the deep 
cruralis before spoken of). In this animal it is very large, and two smaller portions of 
it are separable, and described by Burmeister respectively as vastus externus inferior 
(no. 17 a) and vastus internus inferior (no. 18 a). 
In Cheiromys the crureus is exactly the same as in L. catta; and what Professor Owen 
describes as an outer division of the muscle is in our specimen inseparable (except 
artificially) from the vastus externus. Professor Owen‘ says “The outer division of the 
crureus (fig. 3, 19) is rather a distinct muscle, which might be termed the deep-seated 
vastus externus; it arises from the fore and outer part of the femur to the condyloid 
1 Loe. cit. p. 72, tab. 3. fig 1. 2 Loc. cit. p. 73, tab. 4. fig. 5. 
3 Trans. Zool. Soc. vol. v. p. 66, pl. xxv. figs. 2 & 3. 
