No. 3.] MUSCLES AND NERVES IN AMIA CALVA. 655 
large triangular terminal piece which to all appearances is 
simply the greatly enlarged cartilaginous proximal cap of the 
element. In it is found the second, and perhaps secondary, 
ossification of the piece, the relatively small semicircular bone 
considered by Bridge as an epihyal. The free straight edge of 
this ossification forms the larger part of the dorsal side of the 
triangular cap of the element, but it does not extend quite to 
the upper tip or quite to the lower edge of the cap. Its semi- 
circular side is thus left entirely surrounded by cartilage, and 
the bone touches and is connected with the large lower ossifi- 
cation only by means of a small thin splint-like process, which 
projects downward from its outer surface at its lower corner 
and dove-tails into a corresponding depression on the outer 
surface of the dorsal edge of the lower bone. Near the upper 
end of its straight, free edge, and directed at right angles to 
that edge, there is a strong condylar process always strongly 
capped with cartilage, the cap being sometimes connected with 
the main cap by a narrow line of cartilage along the upper, 
dorsal edge of the element. On the flat outer surface of the 
ossification there is a large depression in which the upper pos- 
terior end of the ligamentum mandibulo-hyoideum (/wh) is 
inserted, and it is around this point as a center that the ossifi- 
cation is formed. A bone having the shape of the one shown 
in van Wijhe’s Fig. 13 I did not find in any of the specimens 
examined, but I do not doubt that, in specially developed 
specimens, it may exist. 
The epihyal (2/7), or next following member of the arch, is 
the interhyal of Bridge and van Wijhe. It is a small rhom- 
boidal piece of cartilage articulating with the condylar process 
of the ceratohyal, and directed upward, forward, and slightly 
inward in the line of the long axis of the hyomandibular, at 
right angles to the lower edge of that bone, and at right angles 
to the axis of the upper end of the ceratohyal. Its flat surface 
is perpendicular to that of the hyomandibular and perpendicular 
also to that of the blade of the ceratohyal, the edge of the 
piece being, therefore, presented laterally. Its inner edge is 
longer than the outer one, and lies in the plane of the inner 
surfaces of the hyomandibular and the blade of the ceratohyal. 
