330 MR. ST. G. MIVART ON THE ANATOMY OF ECHIDNA HYSTRIX. 
Latissimus dorsi (Plate LII. figs. 1 & 3, 1.01 & r.p 2).—There are two distinct 
muscles, which seem to me together to represent the latissimus dorsi. 
The posterior one of these is very elongated, and is triangular in shape from its origin 
as far as the elbow. It arises, by digitations, from six ribs (namely, from the eighth to 
the thirteenth), and, becoming narrower, passes beneath the interior condyle. A little 
below the middle of the forearm it becomes intimately united with the surface of the 
flexor carpi ulnaris. The anterior muscle is wider but shorter than the preceding; it 
arises from the spines of the first eleven dorsal vertebræ, and also somewhat from the 
ascia. lumborum. It is inserted into the inner condyle of the humerus, in union with 
what appears to be the dorso-epitrochlear. 
Serratus posticus.—I did not observe the presence of any serratus posticus ; and both 
Meckel and Owen are silent respecting its existence in the Ornithorhynchus. ` 
Splenius.—This muscle arises from the spines of the most anterior dorsal vertebræ 
and from the midline of the back of the neck, and is inserted into the posterior part 
of the cranium towards the outer side. è 
The sacro-lumbalis is weak and thin, and, leaving the common mass of the erector 
spine, is inserted into all the ribs. It is rather widely separated from the outer margin 
of the longissimus dorsi. 
The cervicalis ascendens is represented by the single fasciculus and tendon of the 
sacro-lumbalis, which is inserted into the transverse process of the seventh cervical 
vertebra. 
Longissimus dorsi, spinalis, semispinalis, and multifidus spine.—As in the Ornithorhyn- 
chus', these muscles are united into a more or less inseparable mass, which extends 
along the spine from the sacrum to the neck, long and superficial tendons being inserted 
into the spines of all the vertebræ from the fourth cervical to the last dorsal. 
The £ransversalis cervicis is the continuation upwards of the preceding ; it arises from 
the transverse processes of about the six most anterior dorsal vertebræ, and is inserted 
by distinct tendons into the similar processes of the sixth, fifth, fourth, third, and 
second cervical vertebra. 
The trachelo-mastoid is placed just within the preceding ; it arises from the transverse 
processes of the second, third, fourth, and fifth cervical vertebræ, and is inserted into 
what appears to be the mastoidal region of the skull, behind and beneath the insertion 
of the sterno-mastoid. 
Complexus.—This is rather largely developed; it arises from the transverse processes 
of the cervical and the first two or three dorsal vertebræ, and has a strong tendinous in- 
sertion into the skull. 
The rectus capitis posticus major and minor, as well as the obliquus capitis superior and 
inferior, are all normal; but the obliquus superior is very large, thick, and strong. 
The rectus lateralis has also the usual origin and insertion. 
Rectus capitis anticus major.—This muscle is remarkably prolonged, being relatively 
almost as long as, though much more slender than, in Nycticebus tardigradus s d 
* Meckel, loc. cit. p. 24. ? See Proceedings of Zool. Soc. for 1865, p. 241- 
