No. 468] MUSCLES OF ACANTHIAS AND RAIA. 919 
Acanthitas. 
A few short adductor muscle fibers extend between the cerato- 
and epibranchial cartilages of each branchial arch. They have 
their origin in small grooves on the inner surface of the epi- 
branchials and are inserted in similar grooves on the inner 
(dorsal) surfaces of the ceratobranchials. Their function is to 
flatten the branchial region. 
Rata. 
In the skates (Fig. 12, Aad) the adductors of the branchial 
arches closely resemble those of Acanthias. They arise from 







NINN 









NN 
SR S Qae GY / z—— 
RUN SS >= 7 ZEN 
p 
Cor 



Fıc. 14.— Side view of Acanthias after removal of the skin. Am, adductor mandibularis ; 
Cac, coraco-arcualis communis; Csd 1-6, constrictores superiores dorsales ; Csv 1-6, con- 
strictores superiores ventrales ; Csv ra, constrictor superioris ventralis, anterior fibers ; 
Gs, gill slits; A, hinge of jaws; L4s, levator labialis superioris ; Lys, levator maxillz sup- 
erioris ; 77, trapezius. 
and are inserted in similar grooves in epi- and ceratobranchial 
cartilages, while a few of the fibers extend some distance along 
the ceratobranchial before finding their insertion. 
