MORPHOLOGY OF THE EXTENSOR MUSCLES. 7 
I have not met with any description of the nerves of Menobranchus in the 
literature of the subject. The account given by Mrvarrt of the muscles differs in 
several respects from the condition which I observed in my specimen. He 
appears not to have observed the ulnar sector at all; he represents the extensor 
longus digitorum as inserted into the digits, and he describes the extensor brevis 
digitorum in the following words :—“ This is a very small muscle, which arises from 
the radial side of the distal end of ulna, and, passing obliquely downwards and out- 
wards, goes mainly, if not exclusively, to the most radial digit.”* It is evident, 
however, that Humpury found a similar condition in Menobranchus to the arrange- 
ment in my specimen, for he says :—‘“ In Menobranch and Saurians it (extensor 
digitorum sublimis) stops, like its homologue in the hind limb of those animals and 
of Ai, at the metacarpus, being inserted there in three portions ; and small muscles 
arising from the metacarpus, close to its insertions, constitute the only extensors of 
the digits, and pass to the terminal phalanges.” + 
In the lower limb, the superficial stratum arises in part from the lower end of 
the femur, and is in part continuous with portions of the quadriceps extensor (Fig. 
1, ext. 1 and ewt. 2). The mtermediate sector (extensor longus digitorum) arises 
by fleshy fibres from the lower end of the femur immediately above the notch 
between the two condyles, and is also directly continuous, by means of a flattened 
tendon, with the muscle ext. 1. It passes downwards in front of and between the 
tibial and fibular sectors, and ends in three slips which are inserted into the bases of 
the second and third, the third and fourth, and fourth and fifth metatarsal bones 
respectively. The tzbial sector is continuous by an aponeurotic tendon with the 
muscle eat. 2. Its chief origin, however, is by fleshy fibres from the anterior 
surface of the lower extremity of the femur under cover of, and partly internal to, 
the extensor longus digitorum. It is inserted into the whole length of the inner 
border of the tibia, a small slip passing on to the tarsus. The fibular sector arises 
from the front of the external condyle of the femur, and is inserted into the entire 
length of the outer border of the fibula, sending a distinct fleshy slip to the fibular 
side of the tarsus. 
Deep stratum.—The extensor ossis metatarsi hallucis arises by a few fibres 
from the extreme lower end of the fibula, but chiefly from the tarsus, and is inserted 
into the tibial side of the base of the index metatarsal bone. The extensor brevis 
* Mivart. Proc. Zool. Soc., 1869., p. 461. 
+ Humpnry. Jour. of Anat. and Phys., Vol. VI., p. 41, footnote. 
¢ It is foreign to the subject of this paper to discuss the exact morphology of these two muscles. 
They correspond in position to the muscles which are described and figured by Mivarr (op cit. Fig. 9, 
p- 463) under the names of gluteus maximus and rector femoris. These muscles are said, however, to be 
inserted into the bones of the middle segment, which was not the case in the specimen I dissected. The 
point of interest about the muscles is that they are both, very evidently, portions of the extensor mass on 
the extensor aspect of the proximal segment which are in uninterrupted continuity with the extensors which 
are situated below the kneejoint. 
