MUSCLES OF HEAD A\D NECK. ] 7 



by Dobson to be "very feeble " in Centetes ; but in Potamogale is well developed. 

 Dobson's figure of the latter (Dobson, '82- '90, pi. 9, st. h.) shows this muscle 

 in nearly the same proportions as in Solenodon. 



The sterno-hyoid is the most ventral of the muscles of the throat. It arises 

 fi'om the inner or dorsal side of the second segment (mainly) of the sternum. 

 This muscle is divisible into two elements, which, however, are so closely united 

 in the mid-ventral line that the separation is not clearly defined until the invest- 

 ing tissue is removed. The sterno-hyoid is broadly inserted into the ventral 

 surface of the thyrohyal cartilage. 



The sterno-thyroid of each side is smaller than the corresponding sterno- 

 hyoid, and arises just lateral to it. It passes forward along the side of the 

 trachea to the thyroid cartilage, on to the side of which it is inserted by two 

 short muscular branches. 



The crico-thyroid is represented by short muscles on each side, that pass 

 obliquely from the cricoid to the thyroid cartilage. 



Beneath the mylo-hyoid on each side, from the symphysis for about 8 mm. 

 posteriorly, arise the genio-hyoids. They are closely approximated medially 

 and fill the space between the rami. They are inserted on the ventral side of 

 the basi-thyrohyal. 



The genio-hyoglossus is as usual, a thin flat sheet of muscle, arising from 

 the basihyals and radiating out anteriorly to the tongue. 



The trapezius muscles (Plate 4, fig. 1, a, c, d) arise along the mid-dorsal 

 line from the vertebral spines to the occipital crest at the posterior edge of the 

 skull, forming a broad thin sheet. They insert along the spine of the scapula 

 beginning at about 15 mm. from its vertebral edge, forward for some 28 mm. A 

 slight break indicates the division between the spino- and acromio-trapezius, 

 but the latter and the clavo-trapezius are not clearly separable. 



The supracervico-cidaneus (Plate 4, fig. 1, b) arises from the mid-dorsal line 

 of the posterior half of the neck and passes ventrally to become confluent with 

 the broad tendinous sheet attached to the skin along the front edge of the fore 

 shoulder. 



The rhomboideus arises underneath the trapezius, by two heads. The first 

 consists of a single long l^and from the mid-dorsal portion of the neck from occiput 

 to about halfway on its length. The second is a longer sheet from the last cervi- 

 cals and first four or five dorsal spines. The muscle is inserted along the pos- 

 terior inner border of the scapula from just below the angle along the entire 

 vertebral margin . A similar partial division of this muscle was noted by Dobson 



