72 MR. W. K. PARKER ON THE STRUCTURE AND 



The nasal capsules are membranous as yet ; and this crescentic etlmioidal wall, 

 which articulates with the "tegmen," bounds them behind. 



The dorsal element of the mandible, or its "suspensorlum," is the most extraordinary 

 thing in this remarkable "chondrocranium." Each bar is equal in size to the combined 

 trabeculse cranii, and to each is suspended three other cartilages, and a 2^'>'0cess which 

 becomes a free ray (ot.p.). 



The dorsal end of tliis bar early coalesced with, or rather (jrew from, the trabecula, 

 beneath the emerging trigeminal nerve (V.); that part is now narrow, but terete; an 

 elegant crescentic maigin to the subocular fenestra (Plate 2, figs. 1, 2, s.o.f.) is formed by 

 this " pedicle" as it passes outwards and forwards, and becomes the main bar ; that bar 

 is becoming rapidly widened, so as to be five or six times the breadth of the dorsal end. 



A rounded notch exists between the " pedicle" and the spiracular cartilage {ot.p.), 

 and this cartilage is continuous with the tegmen tympani at its distal end, and with 

 the " elbow" of the suspensorlum at the proximal end. 



The "elbow" of the suspensorlum passes outwards into the cheek as a large 

 projection, with a rounded outline ; the bar is then bent in a falcate manner, so as to 

 run into the face where the ethmo-palatine projects. 'In front of this, opposite the 

 middle of the large conjugational tract, there is the jiyriform, gently concave condyle 

 for the cerato-hyal ; it is just beneath the edge of the bar {Plate 2, figs. 1 and 2, hi//.). 



Over this part the larval Batrachian "orbitar process" grows upwards and inwards 

 as a sessile, semi-oval leaf, with decurved edges and a swollen base ; it is attached 

 to the post-palatine crest by a short ligament, and is not confluent as in Bufo 

 vulgaris. 



The decurrent enlargement of its edge runs backwards insensibly mto the main bar 

 as a thickened margin ; in front, it projects over the edge of the bar as a free point, 

 and then runs along the rest of the bar as a selvedge (Plate 2, fig. 1, or.p.). 



From thence the anterior fourth of the suspensorlum is a many-sided flap, not sensibly 

 lessened in width, and having on the outside a snag, and in front the convex sinuous 

 condyle of the mandible {q.), which looks a little inwards, and is only a trifling 

 distance behind the cornu trabeculse. 



That ending, however, is but the heginning of the proper mandible, which is a stout, 

 transversely-directed, sigmoid bar (Plate 10, fig. 5, mk.) ; it is twisted and notched 

 (like the human ulna) to roll upon the quadrate. To its flattened inner (distal) end 

 is attached the lower labial (Plate 10, fig. 5, l.l), a thick, short, arcuate bar, lessening 

 in size downwards, where it is attached by a strong ligament to its fellow to form the 

 horseshoe, or imperfect suctorial disk. The elongated angle of the upper labial ("./.) 

 overlaps the double jaw-piece (labio-mandibular), and is represented by a separate 

 cartilage in the Lamprey, and in the Tadpoles of many kinds of Batrachia. 



The hyoid (Plate 10, figs. 5 and 6, c.hj.) is a large irregular lozenge of cartilage, 

 growing towards the mid-line below, and connected to its fellow by simple cartUage 

 (c.%., h.luj.). Externally, or above (Plate 10, figs. 5 and 6, c.Jiy., st.h.), it sends out a 



