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



therefore aa uninjured oval, having no bevelling or emargination in front ; it forms a 

 fit hd for the vessel of tl:e vestibule {vb.). The stylo-hyal end of the hyoid bar 

 (figs. 2 and 4, st.h.) is small, pedate, and articulates loosely with the ear-mass behind 

 the almost closed first cleft. 



The mandibles (fig. 3) form an elegant arch ; the mento-Meckelian (m.mk.) is not 

 much developed ; the dentary (d.) is small, and the articulare (ar.) is large, has a high 

 coronoid crest, and within its trough behind the articular portion of Meckel's cartilage 

 has a large endosteal nucleus (fig. 3, ar'.), as in Cheloue viridis. The hyo-branchial 

 structures show the same semi-transformed condition as the other parts of the skull, 

 and some very generalised characters, besides. 



At first the stylo-ceratohyal band is narrow (fig. 3, chi/.) ; it then widens largely, 

 narrows again, has a knee-like dilatation at its fore part, and then goes straight back- 

 wards as a narrow hypo-hyal {Ji.htj.). 



The notch between the lateral parts of these structures is three times the extent of 

 the solid basal plate (b.h.hr.) ; and this basal plate has a bony " basi-branchial " {b.hr.) in 

 its centre. The thyro-hyals (t.hy.) are normal, but the posterior lateral lobes are twice 

 as large as those hinder forks, and instead of being a slight cartilaginous snag, they 

 are large, and largely ossified. 



The anterior " lateral lobes" are very large ; they, also, have retained much of the 

 larval cartilage, and each flabelliform outgrowth is notched deeply and sinuously in 

 front. 



The investing bones are very similar to those of newly metamorphosed Frogs and 

 Toads of the more typical sorts. The frontal portion of the two roof-bones (fig. \,f.p.) is 

 merely a narrow lath, lying like a wall-plate on the flat top of the skull-wall ; this ends 

 at the second third of the interorbital region. The parietal portion widens, cover's 

 the hinder part of the large single fontanelle, spreads a little over the temporal region, 

 runs sinuously over the hind skull, and ends some distance in front of the foi-amen 

 magnum. The right bone overlaps the left, and the suture is very irregular. 



The nasals (h.) are large thin shells of bone, coming near each other by their round 

 backs, and having two shallow emarginations outside. The premaxillaries {px.) are 

 of great transverse extent, but their processes are feeble. There are no septo- 

 maxillaries ; the maxillaries {rax.) are long thin bones, with a rather high shell-shaped 

 fore end. 



The quadrato-jugals {qj.) are but Httle united to the quadrate ; they and the 

 squamosals {sq.) are feeble. The parasphenoid (fig. 2, pa.s.) is a short, wide, thin 

 bone, normal in its processes, but ending far behind the antorbital region in a lathy 

 ragged manner, like that of a young Common Frog. The vomers (fig. 2, v.) are very 

 large, have a massive dentigerous lobe that nearly reaches the septum nasi, are coiled 

 ]-ouud three-fourths of the inner nostril {i.n.), and grow out iu front to the suture 

 between the premaxillary and maxillary. 



Here we have a combination of characters that betokens an old type and an arrested 



