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Prof. Huxley on the 



[Mar. 6, 



they are connected together and with the fascia of the external oblique, 

 in the middle line, by a delicate sheet of fibrous tissue (figs. 13 and 15, /) . 

 On comparing this disposition of the tendon of the external oblique 

 muscle with that which obtains in Omithorhynckus (Plate 8, fig. 14) the 

 correspondence is obvious. For, in the latter, the posterior fibres of that 

 muscle are inserted directly into the spine of the pubis (t. p.). Between 

 these and the outer edge of the marsupial bone there is fibrous inter- 

 space, corresponding with the inguinal ring (i. r.) ; while the more 

 anterior fibres of the external oblique are inserted into the apex of the 

 bone, which is, as it were, imbedded in the fascia. If the pedicle of the 

 ypsiloid cartilage were reduced, the rami at the same time widening 

 behind, until their outer angles reached the pectineal processes, and 

 their free apices shortening, the ypsiloid cartilage of the salamander 

 would be converted into two cartilages having exactly the same rela- 

 tion to the tendon of the external oblique that the marsupial bones 

 have in the Ornithorhynchus . 



In the Monotremes (Plate 8, fig. 14, Py.), there are two very large 

 pyramidales muscles, which spring from the whole inner margins of 

 the marsupial bones ; their posterior and middle fibres run to the middle 

 line, but the anterior ones constitute a longitudinal band, which extends 

 forwards, and is inserted along with the rectus (P.), of which, indeed, 

 it looks like a part. In the salamander, muscular fibres similarly take 

 their origin from the inner edges of the rami of the epipubis ; and the 

 most anterior of these fibres pass forwards, and become more or less 

 confounded with the inner edges of the recti (fig. 13, Py.)~ But the 

 region which answers to the lima alba (I. a.) is very broad, whence the 

 pyramidales are separated by a wide interval. 



Thus far, the muscles which are connected with the epipubis are 

 strictly comparable with those which are attached to the marsupial 

 bones. But, in Salamandra, there is a muscle (Plate 8, fig. 13, A.), 

 of which I have been able to find no representative in the Monotremes 

 I have dissected. This is a thin band of longitudinal fibres, which 

 spring partly from the pubis, close to the symphysis, and partly from 

 the outer edge of the pedicle of the epipubis, and are inserted into 

 the outer edge of the ramus (Plate 8, fig. 13, A.). External to this, a 

 broad flat band of muscular fibres (fig. 13, B.) takes its origin from 

 the pubis and its pectineal process, and runs forwards to be inserted 

 into the modified branchial arches and the tongue. These are the 

 liebosteoglossi of von Siebold (" Observationes qusedam de Salamandris 

 et Tritonibus "). Superficial to this muscle, is the proper rectus (-R.) 

 itself, marked by its tendinous intersections ; while, on the dorsal 

 or deep side of both, there is a curious fan- shaped muscle (C), which 

 takes its origin from the pectineal process, by a narrow tendon, and 

 spreads out to be inserted into the outer face of the pedicle and 

 the outer edge of the ramus of its side. The ventral face of the pedicle 



