26 THE DISCOBOLI. 



opposite the upper end of the postclavicula, is attached the lower end of 

 the supraclavicula, a rather broad spatulate bone, which in its upper fourth 

 underlies and is united to the inner side of the post-temporal. 



As a whole, the skull of Cjclopterus (Figure 2 of Plate IX. and Figure B 

 of Plate X.) is short and broad, and in consequence the various bones of 

 which it is composed, and the brain cavity, as also the brain, are to be 

 described in similar terms. The small amount of ossification notwith- 

 standing, the bones may be distinguished with tolerable readiness. On the 

 specimens at hand, not yet fully grown, the bony matter does not extend 

 completely over the space allotted to each, as in better ossified fishes, but 

 the margins are rounded, and spaces are thus left in which there is nothing 

 but gelatinous matter. The bones are squamous ; the thinnest have but a 

 single broad plate of osseous matter. This substance is disposed somewhat 

 in this manner: if the bone reaches but a single surface, the earthy material 

 lies in a thin plate near that surface, while at the inner side of the plate, 

 from its centre of ossification, thin laniince radiate inward and toward the 

 edges ; but if appearance is made at two surfaces, there is a thin plate at 

 each, and these are united at the bony centre by radiating lamince forming 

 cells and chambers between the plates or cups at the articulations. The 

 top of the head is broad and convex ; its outline is subtriangular, the width 

 across the occiput being little less than the length to the mouth. Though 

 uneven, the crown has no great prominence, that of the ethmoid and that 

 of the supraoccipital being the most marked. Each frontal (1) is about as 

 broad as long, and sends out a thin projection to overhang the greater por- 

 tion of the orbit of its own side of the head. The parietals are of me- 

 dium size, flat, wider than long. On the supraoccipital (8) the crest is a 

 low rounded prominence, and the base is comparatively broad and rounded 

 at the lower edge. The paroccipitals also are broad; backward they form 

 a wide blunt angle. Being without deep excavations for the muscles be- 

 tween mastoid and occipitals, the skull presents a full and massive appear- 

 ance in its posterior aspect. On the back the squamosal rises to meet the 

 paroccipital between the mastoid and the exoccipital. In its upper half, 

 the post-temporal (46), thin, short, and moderately wide, is applied to the 

 skull over the suture between mastoid and squamosal ; in its lower half, 

 it is bent downward and lies on the upper portion of the supraclavicula (47), 

 by which means the shoulder girdle is connected with the skull. 



As seen from below, exoccipital, mastoid, and alisphenoid are in con- 



