.,804 EEPORT OF COMMISSIONER OF FISH AKD FISHERIES. [58] 



will be more easily available for those who wish to compare my state- 

 ments with the specimen of the fish before them. 



In the adult Micropterus we find the entire skull very thoroughly 

 ossified, with the vast majority of the bony elements pertaining to this 

 part of the Telesotean skeleton present. Viewing the cranium from 

 above, we have presented us for examination, on its hinder calf, five 

 prominent crests j two on either side and a median one. This latter 

 appears to be developed entirely by the supraoccipital (Plate XI, Fig. 

 27, 8. 0). If the free margins of the lateral crests were produced ante- 

 Tiorly they would all meet at a point just beyond the supraethmoid. 

 The inner pair of these crests are developed by the parietals (Fig. 27, 

 Fa.), and they terminate posteriorly in horizontally flattened processes 

 formed by the epiotics (Up. 0). On the outer side the crests are formed 

 by the squamosals, which in their turn are completed behind by the 

 ^terotics, which here are vertically co^ppressed plates (Fig. 27, 8q. Ft. 0). 

 The crest part of the squamosal is formed of two lamina, between which 

 passes the squamosal mucus canal. A deep sulcus is found between 

 the hinder ends of the parietal and squamosal crests, at the base of 

 which we find a large triangular foramen, covered over in the recent 

 state by membrane, just beyond the squamosal, on either side the 

 crescent-shaped and upper part of the postfrontal {Ft. f). The mid- 

 region of this aspect of the cranium, and constituting the vault of the 

 orbits, is formed by the broad /rentals {Fr.) with a tolerably distinct 

 suture still visible between them. Here an interesting condition of the 

 mucus canals presents itself. This consists in a large V-shaped cov- 

 ered canal with its convex arc just beyond the crest of the supraoccip- 

 ital, where it has in the median line a common opening. The limbs 

 of this covered V pass through each frontal, to open on the surface, in 

 elliptical apertures, a little behind the prefrontals. They then tunnel 

 again to open once more directly forward on either side of the supra- 

 ethmoid and over the surface of the nasals. From our superior aspect 

 we also have a good view of the upper surface of the sculptured pre- 

 frontals (Fig. 27, Frf.), forming the anterior walls of the orbits. Beyond 

 this the region is occupied by the supraethmoid and upper part of the 

 vomer. It is pierced on either side of the promontory formed by the 

 supraethmoid, by the nasal foramen, and the opening for the olfactory 

 nerve. 



Upon a lateral view of the cranium we are to note the deep articular 

 facet for the hyomandibular extending from the postfrontal along be- 

 low the squamosal crest, and occupying the lateral portion of this bone. 



Here we see, also, that the postfrontals dip pretty well down on the 

 lateral wall, wedging in between the alisphenoid and prootic (Fig. 27, 

 As. Fr. 0. and Ft/.). The opisthotics occupy their most usual site in 

 front of the exoccipital on either side. Beyond the alisphenoid I find 

 an ossification I take to be the orhitosphenoid, it is in contact with the 

 alisphenoid behind, runs down the lateral wall of the cranial cavity, 

 while it forms a prominent ridge traversing forwards on the under side 



