Brooks — The Osteology and Arthrology of the Haddock. 167 



If the fresh head be boiled for a short time, all but two of the 

 facial bones (the parasphenoid and vomer) will become detached. 

 These two bones will remain strongly connected to the brain-case, 

 but are not included among the bones of the cranium, as the 

 prootic bends inwards, and articulates with its fellow of the oppo- 

 site side above the parasphenoid, thus entirely excluding the latter 

 bone. The prefrontals in the same way exclude the vomer. The 

 mesethmoid and prefrontal do not appear at first sight to form 

 parts of the brain-case, but it will be remembered that the olfactory 

 nerves pass out between the frontal and prefrontal, and end in the 

 olfactory bulbs (PL YII.,fig. 13, 3), which are morphologically part 

 of the brain. These bulbs lie on the prefrontal, in a hollow bounded 

 by the mesethmoid in front, partly roofed by the same, and 

 bounded laterally by membrane. From between the mesethmoid 

 and prefrontal a strong rod of cartilage projects backwards above 

 the parasphenoid and vomer ; the membranous interorbital septum 

 splits to enclose this, and is attached to the parasphenoid below. 



The hyomandibular, with the symplectic and quadrate, forms 

 the suspensorium. The quadrate, connected to the palate by the 

 three pterygoids, forms, with these bones, the palato-quadrate arch. 

 Thus, from the palate to the hyomandibular there is an immov- 

 ably articulated chain of bones (PL YL, fig. 5), which is strength- 

 ened by a strong splint, the preoperculum, which is united by 

 suture to the quadrate and hyomandibular. This arch articulates 

 in two places with the skull ; the head of the hyomandibular with 

 a cavity formed by the pterotic, prootic, and sphenotic bones ; and 

 the angle of the palate bone with a cartilaginous eminence de- 

 veloped on the junction of the prefrontal and vomer. It is also 

 suspended to the anterior end of the skull by strong ligaments. 

 The quadrate furnishes an articular condyle to the mandible. 



The orbit is bounded above by the frontal and prefrontal. To 

 the side of the latter is articulated a rather large lachrymal, to the 

 back of which is attached a chain of five small suborbital bones, 

 the last of which articulates with a projecting angle of the frontal, 

 thus surrounding the orbit with a bony ring. The lachrymal pro- 

 jects forwards in front of the orbit, overlapping the upper ends of 

 the maxilla and premaxilla, and its internal edge is joined by 

 ligamentous fibres to the nasal, the inner edge of which is con- 

 nected in a similar way to the ethmoid. The posterior portion of 



