924 THE AMERICAN NATURALIST. | (Vor. XXXIX. 
forward and outward, passes the first hypobranchial on the dor- 
sal side, and converges to a small flat tendon on the anterior ven- 
tral surface of the hyomandibula. 
SUMMARY. 
In the foregoing, all of the muscles of the head and the bran- 
chial region, with the exception of the eye muscles, have been 
considered. The two forms studied agree very closely when 
their difference in shape is considered. 
In the skate, as might be expected from its extreme modi- 
fication, a few muscles are developed which are not found in 
the dogfish. These are the levator and depressor of the ros- 
trum, and the cerato-hyomandibularis which, from its position, 
seems adapted to the protrusion of the jaws. 
The muscles of the skate referred to by Tiessing as “ Csvp 
3-5,” are here interpreted as fibers of the interbranchials which 
have acquired an extreme development. 
The muscles in Acanthias, marked Csv 2 and Csß 2 by Vetter, 
are here regarded as the first and second ventral constrictors 
respectively. 
The deeper ventral need muscles of Raia are described 
for the first time. 
LITERATURE. 
DRUNER; L. 
:03. Ueber die Musculatur des Visceralskelettes der Urodelen. Azat. 
Anz., vol. 23, pp. 545-571, 16 figs. 
TIESING, B. 
'95. Ein Beitrag zur Kenntnis der Augen-, Kiefer-, und Kiemenmuskula- 
tur der Haie und Rochen. Jen. Zeitschr. f. Naturw., vol. 30, PP- 
75-126, pls. 5-7. 
VETTER, B. 
"74. Untersuchungen zur vergleichenden Anatomie der Kiemen- und 
Kiefermusculatur der Fische. Jen. Zeitschr. f. Naturw., vol. 8, 
Pp. 405-458. 
