346 HOWARD AYERS 
the mesial faces of the myotomes. 3) Bandlike tendons to the 
ventral edges of the myotomes. Dorsomesad of the dorsal longi- 
tudinal attachment to the myotomes there is a large lymph space 
separating the oral hood from the surface of the myotomes and 
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SISA - i My 
PEO IIS Fe EG AD be. 
Fig. 3 Sagittal section of the head of Amphioxus near the median line to 
show the lower lip, jaw base, velum, and endostyle. The relations of the jaw 
muscles to the parent transverse muscle, to the velum, and to the jaw base are 
indicated. The jaw apparatus is in contraction. 
the notochord across which connective-tissue threads connect 
to the adjacent structures. 
The muscles which move the jaw bars and their tentacular 
projections appear to be derived from the large transverse ventral 
muscle of the body wall (figs. 2, 3, 4, 5, 6, and 7). They consist 
