1904.] OS'fEOLOGY OlF CLUPEOID FISHES. 473 



encloses a vesicle of the swim-bladder, the pre-epiotic fossa above 

 it is rendered very shallow as compai'ed with that of Clupea. 

 The auditory fenestra, opening into the perilymphatic cavity, 

 is bounded by the pro-otic, exoccipital, and basioccipital, as in 

 Clu])ea. 



Text-jfia-. 133. 



Cranium oi Eiigraulis encrasicholus, left side. For explanation of lettering 

 see p. 493. 



The foramen for the trigeminal nerve is of large size ; it faces 

 more anteriorly than usual, and is bounded by the alisphenoid 

 and pro-otic, instead of by the pro-otic alone. The pi'o-otic bulla, 

 like that of the squamosal, is lai-ge ; it is not spherical, but is 

 drawn out in a direction nearly at right-angles to the median 

 plane of the head (see Journ. Anat. and Phys. xxvi. 1891, p. 36, 

 and p. 32, fig. D). A basisphenoid is present, but it has no 

 descending limb. The articulation for the hyomandibular is 

 situated rather far forward ; the anterior head of the hyo- 

 mandibular articulates with the postfrontal, and the hinder with 

 the squamosal. 



The latei'al tempoi-al groove is broad and shallow. Removal of 

 its floor exposes a fairly lai-ge cavity opening laterally by two 

 apertures — one over the articular process of the squamosal for the 

 reception of the posterior head of the hyomandibulai-, and the 

 other immediately in front of this. The cavity is roofed by 

 the frontal, and is bounded in front by the postfrontal, behind 

 by the squamosal, and below mainly by the pro-otic. 



The parasphenoid is depressed at abovit the middle of its length, 

 doubtless in I'elation with the large size of the eyes. It does not 

 project behind the occipital articulation, bvxt it ends posteriorly 

 in a pair of parallel lamellae on the right and left sides of the 

 posterior outlet of the eye- muscle canal. Both parasphenoid and 

 vomer are edentulous. The front of the cranium is formed by 

 the mesethmoid, and not by the vomer (cf. Clwpea). The mes- 

 ethmoid is large, of considerable vertical extent, but thin ; the 

 prefrontals are relatively small. The orbitosphenoid is small, and 



