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



half-grown — or equal to the size of the full-grown individuals of this species. The 

 parasphenoid (pa.s.) is very large, both in its main part and wmgs ; this form is like 

 that of the Common Frog, but the point is longer and sharper. 



The vomers (v.) are typical ; the septo-maxillaries extremely small if jiresent, and the 

 bones of the outer face normal, but .slight. The nasals (».) are long crescentic .shells of 

 bone ; the fronto-parietals (f.p.) are large and out-spread over the hind skull and then 

 become gradually fine sharp styles in front, leaving part of the gu'dle-bone and a little 

 of the fontanelle {fo.) uncovered. 



The "frontal suture" is permanent; the "sagittal" is filled in with l)one ; the two 

 sides being continuous over the inter-auditory region. 



The mandible (fig. 3) is quite normal. 



The stylo-hyal end of the hyoid band (fig. 2, st.h.) is distinct and pointed as it 

 passes behind the Eustachian opening ; this band widens to double its breadth (fig. 3, 

 c.hy.) in the lower half, and tlien turns suddenly round to join the basal plate {h.hy., 

 h.h.hr.). 



Round the outside of the broad distal half there is another band of cartilage as wide 

 as the upper half of the main band. 



Tiiis is an "extra-hyal" element {cx.hij.) ; it pas.ses over the liypo-hyal loop aa a 

 short hook. 



Other Oriental Batrachia show this, but not so distinctly, e.g., Tomopterna, 

 Callula, and Dlplopelma, and the Aiistralian Tree-frogs have a rudiment of it : here 

 it is most largely developed. 



If this cartilage be compared with the pectinate " inter-branchial " of Chimcera 

 (HuBRECHT, fig. 2), it will be seen to correspond with the base of that comb-like 

 cartilage. 



In Tadpoles the extra-branchials send pectinate processes inwards, but they show 

 no separation of the extra-branchial bands from these " rays " of the septa, such as 

 we see in Sharks, for the branchial apparatus of the Tadpole is as highly generalised, 

 as that of the Shark is intensely specialised. 



The "spiracular cartilage" belongs to the suspensoi'ium {of the 1st arcli), and becomes 

 utilised as the annulus tympanicus ; this rarer "extra-hyal" and the four extra- 

 branchials all belong to one categoiy. 



Tlii.s ufero-cxternol element of the hyoid arch, like the siipero-intcyndl (epl-hyal or 

 "columella"), does not appear until after the metamorphosis of the Tadpole; that is 

 utilised as part of the apparatus of the fast-improving ear ; the extra-hyal merely 

 serves as an additional platform for the thin fan-like muscles of the throat. 



The rest of the hyo-bi'anchial structure is quite normal ; the lateral lobes are highly 

 developed, and the thyro-hyals strong (fig. 3, t.hy.). 



Besides the remarkable shape of this skull, so wide behind and so pinched in in 

 front — necessarily modifying the form of the investing bones — we have the subjoined 

 differences from the typical form, viz. ; — 



