No. 3.]} MUSCLES AND NERVES IN AMIA CALVA. 673 
a longitudinal tendon which extends about one half the length 
of the muscle, and is itself inserted on the anterior car- 
tilaginous cap of the first ceratobranchial and on the under 
surface of the bone of that element beyond the cap. A few of 
the proximal fibres of the muscle have a direct insertion on 
the cartilaginous cap itself on either side of the insertion of 
the tendon. In front of this muscle, in the space between the 
distal end of the hypobranchial and the posterior surface of 
the hypohyal, McMurrich found a muscle, but I have been 
unable to find one, or even a trace of one, in any specimen, old 
or young. A strong interarcual ligament was, however, always 
found running from the small process on the front edge of the 
first hypobranchial to the posterior and ventral surface of the 
hypohyal near its articulation with the ceratohyal, as already 
described ; and internal to it, in the space where McMurrich 
seems to have found the muscle referred to, I always found a 
mass of fatty, connective tissue. 
The obliquus ventralis of the second arch (Ov.//) is very 
similar to that of the first, but it extends, at its origin, farther 
forward and it is incompletely separated into a distal and a 
proximal portion. The proximal portion arises, as does the 
muscle of the first arch, from the grooved, ventral surface of 
the shank or straight part of the hypobranchial. The anterior 
portion arises from the ventral edge of the bent end of the bone, 
and its fibres form on the ventral surface of the muscle a 
rounded, nearly separate muscle-belly. In its deeper portion it is 
continuous with the proximal muscle, and the fibres of both are 
inserted on a median, longitudinal tendon lying on the ventral 
surface of the proximal muscle, the tendon and a few fibres of 
the proximal muscle being inserted, as in the first arch, on the 
cartilaginous cap and on the anterior end of the bony portion 
of the ceratobranchial of the arch. 
The obliquus ventralis of the third arch (Ov.///) resembles 
that of the second, but the proximal portion of the muscle, 
owing to the smaller size of the hypobranchial of the arch, is 
relatively much less important, and the fibres of the distal por- 
tion contract more markedly into a tendinous end before their 
insertion on the median tendon of the muscle. The distal 
