226 



ANATOMY OF VERTEBRATES. 



those of the transoersalis ahdommis, and pass forward to be 

 inserted at the end of the bony part of the fourth rib in advance. 

 The muscle answering to the rectus abdominis, ib. A, has the 

 short rib-cartilages for its intersections, instead of the fibrous 

 ' linear transversa;,' as in Man. 



The inter costales, fig. 143, F, have their usual position and 

 decussating arrangement in two planes. Tlie squamo- costales, 

 figs. 143, 144, I, I, arise from the ribs near the insertions of the 

 levatores costaruin, B : these origins have been detached and the 

 muscles reflected ; in the figures they pass obliquely backward, 



and are inserted into 

 the skin near the outer 

 margins of the ventral 

 scutes, 



The scuto-costales, fig. 

 143, II II, rise from the 

 fore part of the end of 

 the rib, and are inserted 

 into the edge of the 

 scute. 



The inter scut ales, figs. 

 143, 144, F, G, K, are 

 in two layers, which 

 decussate each other, 

 and cooperate with the 

 scuto-costales in alter- 

 nately erecting and de- 

 pressing the scutes.' 

 The fixed point of one 

 series is the ' linea aH)a,' 

 ib. E ; of the other, the 

 line of Insertion of the 

 sqnamo-costales, ib. i. 

 The co-ordinate cftects 

 of the foreffoina: mus- 

 clcs of the ribs and 

 scutes produce deter- 

 minate movements, to 

 and fro, of the ribs, with alternate erection and depression of the 

 broad transverse ventral scutes. 



The tympano-mandibular arch has unusual mobility in Ser- 



Jliis.ks ,.r Uiu rlliBHi 



XX. vol. i. pp. 69-72. 



