122 ON SOME AMPHIBIAN AND REPTILIAN REMAINS 
extends backwards beneath the orbit to the posterior margin of the 
jugal bone, where its bony matter disappears. The maxilla is widest 
midway between the nostril and orbit, where it sends up a short. 
obtuse process. 
Immediately above this portion of the mawnilla lies a broad flat 
bone (Pl. XXIJ. [Plate 7] fig. 2), circumscribed on three sides by a 
zigzag suture, whose posterior free edge forms the anterior boundary 
of the orbit, while its anterior margin does not quite reach the pos- 
terior boundary of the external nostril. Its upper edge unites with a 
fragment of bone whose anterior end enters into the boundary of the 
nostril. Inferiorly and behind, it is in contact, for a small extent, 
with a bone (the jugal) which completes the boundary of the orbit 
below ; and, in front of this point, it either comes into relation with 
the manilla, or is separated from it by an elongated bone which com- 
pletes the boundary of the nostril anteriorly. I put the alternative 
because I do not feel certain whether a particular line, which seems 
to be a suture, is one or not. If the elongated strip of osseous. 
matter in question be a distinct bone, it corresponds with that termed 
by Von Meyer “lacrymal” in the Labyrinthodonts. 
The bone bounded by the zigzag suture is in all probability the 
prefrontal, while the upper fragment connected with it is apparently 
all that remains of the nasal. 
The jugal bone (Pl. XXI. [Plate 7] fig. 2) narrows as it passes 
back from its connexion with the prefrontal, becoming very slender 
where it forms the lowest part of the orbital wall. Indeed it here 
exhibits a discontinuity ; but I believe this to be the result of fracture. 
At the posterior part of the orbit i. expands into a broad plate, whose 
anterior concave margin forms half of the posterior boundary of that 
cavity. Its inferior margin unites with the maxillary, and then with 
a small triangular plate of bone interposed between it and the end 
of the maxillary (quadrato-jugal?). Its superior margin is divided 
into two parts,—an anterior, nearly horizontal, which unites with a 
slender plate of bone whose anterior end forms part of the boundary 
of the orbit, and seems to be all that is left of the bone called 
“ post-orbital”” (Hinteraugenhohlen-knochen) by Von Meyer; and a 
posterior moiety, which shelves downwards and backwards and 
articulates with another fragmentary bony plate, whose upper part 
occupies the superior and external angle of the skull, while its lower 
part becomes lost in the outer surface of the mass of matrix which 
has filled the cavity formed by the quadrate and other bones, and is. 
the representative of the suspensorial apparatus of the lower jaw. 
This bone is obviously the squamosal. 
