268 SHOULDER-GIRDLE IN MONOTREMES, 



ridge. The deeper layer (Fig. 2 et 3, Pn. D. 11) sinks beneath 

 the P. major and P. quartus, and is inserted by a narrow tendon 

 on the proximal end of the antero-internal border of the pectoro- 

 deltoid ridge. These two parts together constitute a dermo-Jiexor 

 hrachii. 



Special regions and muscles. — Between the clavicular and man- 

 dibular regions the fibres have no longer an antero-posterior course, 

 but their direction being now at right angles to the long axis of 

 the body they encircle the neck and head, forming a superficial 

 sheet which stretches ventral to the inter-mandibular muscles, and 

 up over the sides of the head, being perforated for the ear and eye, 

 and being attached to the parietal and frontal bones by aponeurosis. 



M. dermo-dorsi cervicalis (Fig. 11, D. D. C). — This band of 

 muscle is displayed when the superficial layer of the panniculus 

 and a thick layer of fascia (which lies immediately beneath the 

 panniculus) are reflected from the postero-dorsal region. The 

 muscle arises by tendons from the 9th, 10th, 11th ribs, the inner 

 margin of the slip from the 11th rib being about 2*5 cm. distant 

 from the mid-dorsal line, while the slips from the 10th and 9th 

 ribs are further removed. These thin bands are very intimately 

 connected with the tendons of the posterior trapezius arising from 

 these ribs. The bands run forward and outwards, and coalescing, 

 form a thin muscular sheet which becomes much wider as it 

 approaches the scapula. The muscle continues its course, lying 

 on the postero-external border of the trapezius, and passing super 

 ficially to the insertion of this muscle on the scapula, it becomes 

 now superficial to the anterior part of the trapezius, and having 

 reached the lateral aspect of the head and neck, the inner border 

 of the muscle fuses with an aponeurosis which connects it with its 

 fellow across the mid-dorsal line, while the remainder of the fibres 

 are lost over the mastoid and squamosal regions of the skull ; 

 being placed superficial to the next division of the panniculus now 

 to be described. 



The dermo-brachio-cephalic bands arise by dorsal and ventral 

 origins. The dorsal band arises by a flat tendon from the parietal 



