No, 468.] MUSCLES OF ACANTHIAS AND RAIA. 899 
median aponeurosis in common with, but ventral to, the second 
(Csv2). Its fibers run obliquely forward and are inserted by 
means of small tendinous portions upon the ventral edge of the 
lower jaw. A few of the more posterior fibers (Csv 7a) are 

Fic. 5.— A deeper dissection of Acanthias. On the right, Csz 7 has been turned back to show 
the whole of Csv 2. Cac, coraco-arcualis communis; CHy, coraco-hyoideus ; Cm, cor- 
aco-mandibularis; Csv 7-2, constrictores superiores ventrales; Csv ra, constrictor supe- 
rioris ventralis, anterior fibers; /»zör, interbranchiales. 
inserted upon the adductor of the lower jaw instead of upon the 
Meckelian cartilage, and here the fibers of CsvI and Csv2 
become fused so that at this point there is no sharply defined 
