of the Fishery Board for Scotland. 257 



Ethmoid (E.). 

 Cod, Fig. 42, PI. IX.: Saithr, Fig. 6, PI. IX.: Lythe, Fig. 21, PI. IX. 



Attached to the base of the ethmoid there is a large mass of cartilage, 

 which is received into the hollow in the upper surface of the vomer, and 

 the long tapering hind end of which passes liackwards into the hollow 

 extremity of the parasphenoid. 



The sutural area of the ethmoid with the frontal is in the saithe and 

 lythe broad : in the lythe the sutural laminse are short ; in the saithe the 

 central laminai are long thin plates. In the cod the sutural area is 

 narrow, but the projecting laminse of the ethmoid are as long as or longer 

 than those of the saithe. In the case of one saithe, a female measuring 

 90 cm. in length, the sutural area was reduced to one long central thin 

 lamina, with a few short lamella? applied to either side of it, and 

 projecting laterally, but separated from the central group by a short plain 

 interval, was a slightly toothed sutural process. 



Frontal {¥.). 



Cod, Fig. 37, PL IX. : Saithe, Fig. 1, PI. IX. : Lythb, Fig. 16, PI. IX. 



With respect to this bone, the differences noted in the description of 

 the skulls were most prominent. The median portion of the hind border 

 projects farther backwards in the cod than in the saithe and lythe. The 

 low frontal spine also serves to distinguish the former from the two 

 latter ; while the highly-arched plates which form the grooves for the 

 supraorbital canal differentiate the lythe from the saithe, in which they 

 are comparatively low. 



Supraoccipital (s. Oc). 



Cod, Fig. 39, PI. IX. : Saithe, Fig. 2, PI. IX. : Lythe, Fig. 17, PL IX. 



The height of the spine on this bone of itself separates the cod, in which 

 it is low and usually somewhat massive, from the saithe and lythe, while 

 the larger angle between the spine and the lateral arms of the supra- 

 occipital in the case of the cod and lythe separates them from the saithe. 

 In the saithe and cod the disarticulated supraoccipital ends anteriorly in 

 a much finer point than in the lythe. 



Basioccipital (b. Oc). 



Cod, Fig. 48, Pl.IX. : Saithe, Fig, 13, PL IX. : Lythe, Fig. 27, PL IX. 



The neck of the basioccipital is rather narrower in the saithe and lythe 

 than in the cod. There is some difference between the three species in 

 respect to the structure of the upper surface of the bone. In the lythe 

 there is a deep cavity running up between the two large hollows in the 

 internal surface of the bone : in the cod there is in this region a wide 

 depression filled up with loose bony matter. 



Parasphenoid (p. S.). 



Cod, Fig. 51, PL IX. : Saithe, Fig. 15, PL IX. : Lythe, Fig. 30, PL IX. 



The points of difference in the parasphenoids have been noted in the 

 description of the skulls. In the saithe and lythe the anterior end of the 



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