24 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY. 
In older specimens this right supraorbital begins now to disappear, 
the disappearance progressing from behind forward as the ensheathing 
ocular-frontal takes its place and function. The remnant of this carti- 
lage (ham. eth.), as it appears at a later stage, when it has been forced 
into the horizontal position (vertical as the fish lies on its side), is shown 
in Figure D. There is no longer a region of close appression without 
trh. sword. dx. ec’eth, &. 
fon exe * 
| 
aed cré. orb. a. 
| Jor. olf. dx. 
“a ed pt-pal. dz. 
| See bet as PPL No EOD ET A fe Ak er OOS ee eee 
Holy Coa 
Same model as that shown in Fig. C, viewed obliquely from right side and 
behind. A probe is thrust through the right olfactory foramen. X 40. 
For meaning of iettering, see Abbreviations under Explanation of Plates. 
fusion between it and the median arch, but the hook arises directly from 
the arch. 
In Figure Ca bristle is shown passing through the left olfactory for- 
amen, to indicate the axis of the opening, which now is not parallel to 
the longitudinal axis of the fish, —as the right olfactory foramen still 
is, — but makes with it an angle of about 45 degrees, being directed 
caudad, mediad, and dorsad. In Figure C’ a white probe marks the 
position and direction of the right opening. 
