MYOLOGY OF REPTILES. 225 



scmispinalis dorsi, and partly to its insertions into the neural 

 sjiines ; its I'uremost attachment is to tlie superoccipital. The 

 third (neurohiteral) tract derives fibres from the tendinous origins 

 of the longissimus dorsi, and detaches from its outer side tliin 

 slips, each inserted by a slender tendon into a rib ; it represents 

 the sacrohmihalh. A muscle deriving slij)s of origin from the 

 zygfipopliyses of four or six anterior vertebra; passes forward to be 

 inserted into the mastoid, fig. 145, r, and represents the trachelo- 

 mastoideus. On the under part of the vertebral centrum are a 

 series of oljlique fasciculi, extending and converging in pairs from 

 the diapophysis of one vertebra to the hypapophysis of the second 

 or third vertebra in advance. The lonrjus colli at the fore 

 or upper part of the spinal column in Mammals and Man is a 

 rei)etition of this series ; the greater extent and developement of 

 wluch in Ophidians is indicated by the numljcr and length of the 

 hypapophyses, //,//, figs. 46, 47 : and of the subdiapophyses, d' , 

 fig. 47 a ; and these are maximised in Crotalus and Naia ; tlie 

 co-related muscle, having its fjremost insertion into the occipital 

 hypapophysis, fig. 146, p, brings down the head in the blow 

 inflicted Ijy the venom-fangs with proportionate force. 



On removing the semispinalis dorsi, muscles appear which pass 

 obliqiiely Ijetween the transverse and spinous processes, like the 

 series called midtifidus spinoi in Man. Beneath these are inter- 

 spinales and intertransversales. External to the multifidus spinas 

 is a series of levatores costarum hreviores, fig. 14.3, B, arising 

 from the chapophyscs, and respectively inserted into the rib of 

 the succeeding vertebra. At their insertion arise the pretra- 

 heiites costarum, ib. C, which run more obliquely l)ackward, 

 and terminate each in the eighth (Naia) rib beyond that 

 from which it arose ; being attached also to the intermediate 

 ribs and intercostal fasciaB. In Python they are continued on 

 to the tenth or twelfth rib, fig. 14.3, D, and these continua- 

 tions have been described as a distinct series. Beneath them 

 is a shorter series, the pretralientes hreviores, ib. E. The retra- 

 hentcs costarum, fig. 144, C, arise from the lower part of the 

 diapophysis, and pass obliquely forward and outward along the 

 internal surface of the ribs to be inserted into the fourth rib in 

 advance. Where these muscles terminate, the transversalis ahdo- 

 minis, ib. D, takes its serrated origin ; its fibres descend obliquely 

 forward and terminate, with those of the opposite side, in the 

 ra})he, or medial tendinous line ; which closely adheres to that 

 part of the inserted border of the ventral scutes. The retraJientes 

 inferiores, ib. B, interdigitate at their origins (in Python) with 



VOL. I. Q 



