THE PROSOMATIC SEGMENTS OF AMMOCG:TES 293 
which is clearly serially homologous with the other branchial bars, is 
composed of muco-cartilage, and not of cartilage. If we follow this 
series of horizontal sections nearer to the origin of the cartilaginous 
Fic, 116.—HorizontaL SECTION THROUGH THE ANTERIOR PaRT OF AMMOCETES, 
IMMEDIATELY VENTRALLY TO THE AUDITORY CAPSULE. 
sk,-sk,, skeletal bars; m,-m,, striated visceral muscles; mt,-mt,, tubular muscles; 
br,-br;, branchie; i7., trabecule; inf., infundibulum; ped., pedicle; V., tri- 
geminal nerve. Muco-cartilage, red; soft cartilage, blue; hard cartilage, purple. 
bars from the sub-chordal cartilaginous rod on each side of the noto- 
chord, we obtain a picture, as in Fig. 116, in which each branchial 
segment is defined by the section of the branchial cartilaginous bar 
