17G MR. Vr. K. PARKER OX THE STRUCTURE AND 



tract under the liinci Inaiii ; its greatest width is in front. Another tract, twice a-s 

 ]ai-ge, with its base in front, is seen under the pituitary body, and the triangular super- 

 orbitals (s.oh.) are soft. Witli. these exceptional tracts, all the cranium is solid bone 

 up to the middle of the proper nasal region. The fontanelle (fo.) is a long oval ; it is 

 half the length of the cranial cavity, and half the width of the interorbital region at 

 its narrowest part. 



The temporal shoulders of the hind skull are high and large ; from thence the outline 

 narrows suddenly, and. less rapidly I'egains its inter-temporal width, so that the inter- 

 orbital region is at first very narrow, with a deep, large, crescentic emargination 

 right and left ; a small round notch is seen between the superorbitals and the ethmo- 

 palatines. Then the wide gii'dle-bone is flat above and concave on each side below ; 

 moreover, the edge of the cranial boat is pi'oduced outwards, and is scooped below up 

 to tlie optic fenestra. The girdle-bone takes up all the ethmoidal wings, but leaves 

 the facial region of the ethmo-palatines untouched ; in front it occupies full half of 

 the partition wall, the roof, and the floor of the true nasal i-eglon, besides its own 

 ethmoidal wall, roof, floor, and wings. 



From below, the skull looks very much like the repetition, in front, of sucli a 

 continuous vertebral tract as is seen in ihe neck of a Skate. The nerve-passages in tliis 

 flat skull are almost inferior in position, and they form a double series, right and left., 

 in a very orderly manner, and are almost equidistant ; moreover, those for the 

 trigeminal and facial (fig. 7, V.) ai'e subdivided by a bony bar, like those for the glosso- 

 pharyngeal and vagus (IX., X.) : the optic passage is small. 



The nasal roof (fig. 6, each side of s.n.) is wide behind and narrow In front ; the 

 floor (fig. 7, s.n.) is wide at both ends and rather contracted, by a crescentic retreat of 

 the margin, in the middle. The internal nares ('.».) are very large, turn inwards in 

 front, and lie against the narrowing hind part of tlie flooi'. Tlie outer nostrils (e.n.) 

 are only half as large, and half as wide apai't ; they are well protected by the two 

 upper labials (ii.l^.ii.l-.) right and left. The snout is not of great extent, but it is 

 directly transverse, and has no rostrum ; the pro-rhinals [p.rh.) are rather small, but 

 the angles of the floor are large and fan-shaped, and lie well within the wide maxil- 

 laries {mx.). The ethmo-palatines (e.pa., pa., 2'>f/-) are widely transverse, and end in 

 an adze-shaped dilatation externally; the palatine bone (j^a.) takes on the same 

 form, and ends inwardly as a sharp point far from its fellow bone ; the post-palatine 

 cartilage is continuous with the pterygoid tract, which is strongly arcuate, but very 

 narrow and slight; its bony correlate (pg.) runs nearly to the palatine in front, and 

 behind, forks at less than a right angle, in which space thei'e is a very large egg- 

 shaped Eustachian opening {eii.), the narrow end of v^hich is in the sharp re-entering 

 angle of the bone, and is therefore turned outvA'ards. The outer fork binding the 

 quadrate bar runs far back; the inner, growing over the stunted "pedicle" (pel.), clamps 

 it and ties it down to the skull by sutural teeth, instead of allowing it to glide on the 

 corresponding cartilage. The quadrate-condyles {<j.c.) are twice as large as the occi- 



