WILLIAMS: MIGRATION OF EYE IN PSEUDOPLEURONECTES. 23 
sworb. dx.), a8 but now described for the specimen that had lost the left 
eye, is the backward extension of a plate of cartilage which connects the 
right ect-ethmoid with the median mes-ethmoid arch. This flattened 
anterior portion of the right supraorbital cartilage corresponds to the 
tegmen cranii of the right side of the head in the salmon. The median 
mes-ethmoid arch is, at its anterior end, fused to this plate or partial 
t 
tro. sworb. dx. tro. ec’eth. S. 
| 
ee 
4 for. olf. s. 
! 
for. olf. dan! _ ert. orb. a. 
eceth, dz. é pl-pal. a. 
{ 
From photograph of wax model of the facial cartilages of a large specimen of 
P. americanus intermediate between the stages shown in Fig. &. and 
Fig. D. Viewed from a point nearly in front, only a little to the right of 
the sagittal and a little above the horizontal plane. x 45. 
For meaning of lettering, see Abbreviations under Explanation of Plates. 
tegmen, but from the short region of fusion backward for some distance 
the two cartilages are merely crowded closely together, a distinct line 
of perichondrial connective tissue being found between them. The car- 
tilages then diverge, as may be seen in Figure C’, and the median mass 
continues backward as the fused trabecule cranii, while the higher, lateral 
portion, the right supraorbital bar (trd. sw’orb. dx., Figs. C and C’), 
passes upward and backward to the ear capsule. 
