MYOLOGY OF THE ORNITHORHYNCHUS. 129 



runs up the back and sides with uninterrupted longitudinal fibres. On 

 the ventral surface of the tail, there is a similar coalescence of the 

 two sides, at a point just in front of the anus, or just behind where 

 the intertibialis crosses from one side to the other ; the plane, thinner 

 than that on the back, runs uninterruptedly up over the belly. 



Some distance behind the leg, the longitudinal fibres part on the 

 side of the body preparatory to forming the leg-opening. But across 

 the triangular space that would thus be left, semicircular loops are 

 thrown, with less and less belly from behind forward, until they 

 are nearly transverse just at the back of the leg; these sweep around 

 the leg on both sides, embracing it and then coming together again in 

 front of it; the opening thus made is pyriform in shape, with the point 

 forward. A little above the heel, the muscle and skin together are 

 pretty firmly attached, not only to a naked space on the tibia, but by 

 dense areolar or fascial extensions, containing much fat, betwixt 

 the tendons of the muscles. 



Where the intertibialis crosses, this is firmly connected with the 

 panniculus, though not to any special detached slip of the latter that 

 we could discover. 



Uninterruptedly surrounding the whole body, and with simple lon- 

 gitudinal fibres, the muscle runs up to the neck. The provision for 

 the arm-opening is essentially the same as that for the leg-hole, only 

 the point of the pyriform orifice is directed backward ;. the muscle de- 

 scends on the arm; some fibres have definite attachment to the lower 

 third of the ulna ; others less definite fascial connection on the other 

 side, with the lower end of the radius, and with the septa betwixt the 

 flexor tendons of the wrist. 



A few longitudinal fibres are continued from the breast up to the 

 neck; with the exception of these, and of the hyoid fasciculus, to be 

 presently noticed, the fibres are here transverse, without a median 

 raphe, and. sweep over the sides of the neck; they extend quite to the 

 back, and overlie the cheek-pouches. These transverse fibres, and in 

 general, all of the muscle upon the ventral aspect of the body, are thin- 

 ner than those on the dorsal ; and there is a remarkable thickening, as 

 a longitudinal band, along the side of the neck, formed in a manner 

 noticed below. 



Its special slips and their attachments. An hyo-dermal muscle is thus 

 formed : Over the episternal bar, a curved fan- or horn-shaped set 

 of fasciculi are developed from the inner surface of the panniculus ; 

 these curve inward as they pass forward, narrowing to definite fleshy 

 insertion into the body of the os hyoides, on either side of its median 

 line, in mutual apposition. A brachio-dermal is formed over the latis- 

 simus and side of the thorax generally, by a heavy reenforcement to 

 the inner surface of the muscle, of a broad, fan-shaped plane growing 



