294 MR. R. H, BURNE ON THE [Apr. 18, 



vertebrae iv., v. Insertion : the hinder margin of the parietal 

 between the insertion of the testo-occipitis and the mid-line. 



This muscle usually takes origin from vertebra? iii., iv., v. 

 (Bronn's ' Thierreich,' Bd. vi. Abt. iii. p. 79.) 



Testo-cervicalis (text-fig. 55. 16). — This muscle can be separated 

 into a superficial and a deep part : — 



(a) Superficial part. — Origin : the nuchal plate parallel to the 

 anterior border of the scapular articulation. Insertion : the 

 latero-dorsal parts of vertebrae iii., iv., v., vi. 



(b) Beep part. — Oiigin : the carapace along the median border 

 of the scapular articulation. Insertion : doi'sal surface of vertebra? 

 v., VI., VII. 



The two parts of the muscle form a very powerful mass, clearly 

 separable in fi'ont and at their origin, but fused posteriorly. 

 The muscle does not agree very well with the description of any 

 of the neck- muscles given by Hofiinann in Bronn's 'Thierreich,' 

 but most nearly resembles the testo-cervicalis, especially that of 

 Trionyx, which rises from the nuchal plate and is inserted upon 

 the 7th vertebra. 



Transversalis cervicis (text-fig. 55, 17). — Origin : the lateral 

 parts of vertebrae iv., v., vi., vii. above the transverse processes. 

 Insertion : basioccipital and posterior zygapophyses of vertebrae 

 I., II. 



This muscle is the most lateral of the strictly dorsal neck- 

 muscles. In other Chelonians it seems (HofiTmann, p. 80) to rise 

 further forward and not to be inserted upon the skull. 



Testo-ce7'vicalis lateralis {text-'&g. 55. 18). — Origin: by several 

 flat strands from the deep surface of the testo-capitis near its 

 origin. Insertion : by a round tendon to the transA^erse process 

 of vertebra ii. in conjunction with part of the sphincter colli. 



Sphincter colli (text-fig. 55. 1 9). — A sheet of muscle that covers 

 the front of the throat from the tij) of the posterioi- cornu of the 

 hyoid to the clavicle. It varies considerably in muscularity in 

 different parts. At its anterior and posterior ends it is strongly 

 muscular, but in its central parts almost entirely fibrous and 

 quite thin. It is inserted along the sides of the cervical vertebrae 

 from the ii"*^ backwards and to the inner antei'ior border of the 

 scapvila. I can find no mention of the sphincter colli being 

 attached to the scapula in other Chelonians. 



Mylo-hyoideus (19ffi). — An anterior extension of the sphincter 

 colli sheet. Insertion : into the whole length of the inner surface 

 of the mandible, just ventral to the genio-hyoideus, and by a 

 small separate slip into the squamosal in the middle of the origin 

 of the squamoso-maxillaris. 



Capiti-plastralis (text-figs. 55 & 59. 38). — A sheet of muscle 

 covering the venti'al sui'face of the throat deep to the sphincter 

 colli. Insertion : the outer end of the clavicle, the lateral parts 

 of vertebrae ii,, iii., iv., and by a separate and very definite slip 

 into the inner surface of the squamosal, just dorsal to the dilator 

 tubae. 



