PROEESSOR WOOD ON THE NECK- AND SHOULDER-MUSCLES. Ill 
muscle from the scalenus joins it. I have also found it in the Weasel and Badger, Dog 
(fig. 27), and Cat. In the Rodents Cuvier figures it in the Marmot, Beaver, Porcupine, 
and Agouti. It is not mentioned by Mivart and Murie in the latter animal. I have 
found it long, well marked, and overlapping the rectus in the Norway Rat and in the 
Squirrel, connected with the first rib between the subclavius and scalenus , crossing the 
upper part of the rectus , which reaches to the first rib, and reaching far down the 
sternum to join the pectoral fibres arising from that bone (Plate X. fig. IS, n ). In 
Cuvier and Laurillard’s plates it seems to be the muscle marked as the lower part of 
the scalenus , and figured as a very large muscle in the Bradypus tridactylus and Tamandua, 
reaching from the first rib to the eighth, between the pectorals and serratus marjnus. In 
Meckel’s description of the Two-toed Anteater, he describes a long muscle arising from 
the first rib, and inserted into the front part of the ninth, tenth, and eleventh, under the 
name of “ tier kleiner Brustmuskel,” stating expressly that it is not attached to the 
scapula, but that it seems to be an elongation of the external intercostal (Archiv, Bd. v. 
lift. i. p. 41, c ). This is evidently a muscle of the same nature as our human supra - 
costalis, and agrees more with the sterno-costal of the other Mammalia than with the 
rectus thoracicus, which is coexistent and well developed in the same animal. The same 
muscle is figured in this animal by Cuvier and Laurillard (pi. 257. figs. 2 & 6) as the 
anterior scalenus ; but as it commences clearly at the first rib, and does not ascend into 
the neck, it cannot be admitted as entitled to this name. 
In the Elephant the sterno-costal muscle seems to be represented, according to the 
same authorities, by a large muscle, attached on the one hand by three digitations to the 
first rib, and on the other to the side of the upper pieces of the sternum, reaching as 
low as, but not overlapping, the upper insertion of the rectus abdominis. By some this 
may be considered as a rectus sternalis with an interruption of the nature of a tendinous 
“inscription;” but the appearance of the muscle agrees best with that of the sterno-cos- 
talis, while a tendinous separation or interval between the rectus thoracicus and the 
rectus abdominis is not usually seen in the Mammalia. In the Peccary it is composed 
of two large digitations quite unlike a rectus sternalis ; and in the Pig, the anterior fibres 
of the most anterior intercostal muscle cross superficially over the second rib-cartilage to 
be inserted into the sternum below it, showing a feeble development of the sterno-costalis 
or supracostalis muscle. In the Ass the muscle is represented by one digitation only. 
Upon the whole it seems to me that the balance of facts is more in favour of the 
identity of the human abnormal supracostalis muscle with the sterno-costalis of the 
Mammalia, than with the rectus thoracicus of these animals, as in the homology proposed 
by Professor Turner. Finally, I woidd refer to the same supracostal or sterno-costal 
third, and fourth ribs, and inserted into the edge of the first rib near the point corresponding to the insertion 
of the scalenus anticus in Man. The artery of the fore limb crossed its insertion. It was in close contact with 
the scalenus, indeed some of its fibres joined that muscle” (op. cit. p. 297 and pi. 6). This description clearly 
answers to the sterno-costal muscle figured by Cuvier and Laurillard in the same animal. 
