DEVELOPMENT OF THE SKULL IN THE LACERTILIA. 
Gil 
The malar or j ugal is its second splint: in the Lacertilia generally there are no others ; 
inside the jugal the endoskeletal part is absent. 
The isthmus connecting the cartilage with the nasal wall is a secondary or con- 
jugational part; the “ heel ” is the distal end of the arch, the “ toe ” the rudiment of 
the sub-ocular bar. 
This rudiment is well seen in the Chamadeon—the most aberrant form of the Lizard— 
but not in the Snake; in the Birds it can frequently be found. 
In the “ Batitse ” it does not ossify (“ Ostrich’s Skull,” Plate 10, figs. 1, 4, 10,18 ; and 
Plate 14, figs. 1 and 7, a.i.t.), but in the “ Carinatse ” it is ossified as the “ os-uncinatum,” 
and is well seen in Musophaga, Corythaix, Trogon, and Scythrops ; in the “ Psittackke 
in Psittaciform Finches, e.g., Coccothraustes; in Dicholophus; in the “Laridse;” and 
in Diomedea. 
In the “ Ichthyopsida ” it is well developed in the Batrachia, although not often 
distinct from the pterygoid cartilage; in the Urodeles it is distinct, but generally fuses 
with the ear-capsule. 
In the higher “ Ganoids ” it has evidently become fused with the pterygoid, but has 
its own bony centre. (See Traquair on Polypterus, ‘ Journ. of Anat. and Phys.’, 
vol. v., plate 6, fig. 6, pi. ; and Bridge, on Amici, ibich, vol. xi., plates 23, fig. 6, pi.). 
I am somewhat doubtful of it in Acipenser and Polyodon ; in the Sharks it is 
rudimentary, is distinct in Notidanus, and large in all the Skates. 
In every case, even where, as in the Skates, it is most developed, the eyeball thrusts 
it out from the basis-cranii, and has manifestly robbed it of its segmental nerve 
(the third or “ motor oculi ”), and has left it to its own moiety of the 5th, and to a 
wandering branch of the 7th, the “vidian” nerve. 
The 1 1th section (Plate 45, fig. 1) is through the fore part of the eyeball (e), 
and the widest part of the palatine bones (see Plate 42, fig. 2, pa.), where they over¬ 
arch the narial passage (i.n.). 
The septum (now the “ ethmoid ”) is complete here, but enlarged above and below ; 
near it, above, we see the narrow front fork of the orbito-sphenoid ( o.s .). (See also 
Plate 43, figs. 7 and 8, o.s.) 
In this section the foremost large, and a smaller, superorbital (s.ob.) are severed ; 
and the jugal process of the maxillary (rax.) is seen under the eyeball. 
In the 12 th section (Plate 45, fig. 2), both the upper and lower forks of the orbito- 
sphenoid (o.s.) are severed, and the interorbital notch (i.o.n.) is shown in the deficiency 
of the mid-wall above. 
bring the evidence of the best experts on Embryology as to the presence of a true visceral arch over and in 
front of the month (see Balfour, ‘ Elasmobranchs,’ plate 14, pp. 211-216, where the head cavities are 
shown to be continued in front of the mouth; and Milnes Marshall, ‘ Quart. Jour. Micr. Soc.,’ vol. 18, new 
series, plates 2, 3, pp. 1-31, who shows that the 3rd nerve is as good and clear a “ segmental” nerve as the 
trigeminal). I have another—the foremost visceral rudiment in front of the palatine—ready for acceptance 
as soon as this is disposed of. 
