400 MR. ST. G. MIVART ON THE ANATOMY OF ECHIDNA HYSTRIX. 
persistent non-development of the tibial (lesser) trochanter ; but these animals present us 
with another homological indication in the position of the pneumatic foramen, which, 
in the leg opens upon the extensor surface of the single and peroneal (greater) tro. 
chanter; while in the wing the corresponding opening is, indeed, situated on the ex- 
tensor surface, but on that of the ulnar (or lesser) tuberosity, and not upon the radial 
(or greater) one. 
In some reptiles, e. g. in the Chelonions !, as before observed, the most complete and 
striking similarity exists between the humerus and the femur, and between their respec- 
tive tuberosities and trochanters ; while in other reptilian forms great differences present 
themselves in regard to the size and development of the several prominences. 
If, as I believe, there is this relation of serial homology between the tuberosities and 
trochanters, then there is a primé facie probability that a similar relation will be found 
to exist between the muscles respectively inserted into those processes, the more important 
relation of a muscle being, generally, its insertion. We may then expect to find that 
the supra- and infraspinatus, with the teres minor (all inserted into the radial tuberosity), 
correspond with the ¿iliacus and psoas (inserted into the tibial trochanter), and that the 
subscapularis and feres major (attached to the ulnar tuberosity) answer to the muscles 
inserted into the peroneal trochanter, i. e. to the glutei. 
Now this latter resemblance is exactly what exists in the Echidna; and it would be 
highly interesting to know whether this similarity is also present in the muscular struc 
ture of Reptiles and Amphibians. 
Should it turn out to be the case that the true muscular relations are such as I have 
suggested, it would probably go far to settle the interesting question as to what paris 
of the ilium really answer to the several parts of the scapula. 
In the skeleton of an ordinary quadruped (or in that of Man when put in a cor 
responding attitude), in order to place the humerus and femur in the proper position 
to exhibit their serial homologies (with both extensor surfaces outwards), the elbow 
must be drawn outwards and forwards, and the knee outwards and backwards; but 
one is tempted to ask (as has already been done by Dr. Humphry in the passage 
above quoted), why should not the bones from which the humerus and femur are sus- 
pended participate in the rotation? If they are made to do so (and in Galeopithecus’ 
they are naturally somewhat in this rotated position), we then get the axillary margin 
and point of attachment of the £riceps in the scapula, and the anterior border and point 
of attachment of the rectus femoris in the ilium, both turned outwards, while the subse 
pular fossa of the scapula and the outer surface of the ilium both look backwards, and 
the supra- and infraspinatus fossæ and the inner surface of the ilium are both forw ardly 
directed. 
In this position (when the human scapula and ilium are compared) the coracoid seems 
to answer to what I believe to be its true homotype, the ischium, in its relation to the 
; . id of 
: * See, e. g., Trionyz in the British Museum, and Chelydra Temminckii in the Museum of the Royal College ^ 
urgeons, 
* See the skeleton, no. 4630 c, in the Museum of the Royal College of Surgeons. Mr. W. H. Flower kindly 
directed my atteation to this skeleton. 
