MYOLOGY OF REPTILES. 225 



semispinalis dorsi, and partly to its insertions into the neural 

 spines ; its foremost attachment is to the siiperoccipital. The 

 third (neurolateral) tract derives fibres from the tendinous origins 

 of the lono-issirnus dorsi, and detaches from its outer side thin 



o * 



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

 the sacrolumbalis. A muscle deriving slips of origin from the 

 zygapophyses 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 oblique fasciculi, extending and converging in pairs from 

 the diapophysis of one vertebra to the hypapophysis of the second 

 or third vertebra in advance. The lone/us colli at the fore 

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

 repetition of this series ; the greater extent and developement of 

 which in Ophidians is indicated by the number and length of the 

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

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

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

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

 inflicted by the venom-fangs with proportionate force. 



On removing the semispinalis dorsi, muscles appear which pass 

 obliquely between the transverse and spinous processes, like the 

 series called multifidus spina in Man. Beneath these are inter- 

 spinales and intertransver sales. External to the multifidus spinae 

 is a series of levatores costarum breviores, fig. 143, B, arising 

 from the diapophyses, and respectively inserted into the rib of 

 the succeeding vertebra. At their insertion arise the pretra- 

 hentes costarum, ib. C, which run more obliquely backward, 

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

 from which it arose ; being attached also to the intermediate 

 ribs and intercostal fascite. In Python they are continued on 

 to the tenth or twelfth rib, fig. 143, D, and these continua- 

 tions have been described as a distinct series. Beneath them 

 is a shorter series, the pretrahentes breviores, ib. E. The retra- 

 hentes 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 transversals abdo- 

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

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

 raphe, or medial tendinous line ; which closely adheres to that 

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

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



VOL. I. Q 



