1(^0 MR. W. K. PARKER ON THE STRUCTURE AND 



{ex.hij.). The front notch of the basal plate (b.h.hr.) is deep, the plate itseLf of 

 normal length and width, but the front lateral lobe is absent ; the hind lateral lobe 

 and the ossified thyro-hyals {t.hy.) are normal. 



The investing bones are, on the whole, like those of a very young Frog ; but the 

 fronto-parietals (fig. &,f.p.) are small, falcate shells of bone; their ragged inner edges 

 pass a very little way beyond the boundary band of cartilage, behind ; they expand 

 over the antero-medial part of the ear-masses, but are wide apart even there. 



The nasals [n) are normal, but cover only a third of the roof cartilage ; there are 

 no septo-maxillaries, and the marginal bones {px., inx., q.j., sq.) are feeble and thin, 

 like those of young Common Frogs. 



The parasphenoid (fig. 7, pa.s.) is relatively large and well developed; all its pro- 

 cesses are pointed at their free ends, and the basi-temporal projections are uncinate. 

 The vomers {v.) are small, arrested, tootliless, sub-falcate, and rather ragged tracts of 

 bone, like those of the young of any normal type. 



The figures show, of themselves, how far short this small Frog comes of the develop- 

 ment seen in its nearest Ethiopian and Indian relations ; it falls short of the " norma" 

 in the following particulars : — 



1. The arrest, during an early larval condition, of the chondrocranium, both above 

 (in front) and along the sides. 



2. The feeble ossification, especially in the ethmoidal region, so that the girdle-bone 

 is but little developed, broken up into three centres, and widely unfinished, below. 



3. The distinct prenasal rostrum. 



4. A very lai'ge, open, main fontanelle. 



5. A bilobate superorbital (and preorbital) tract. 



6. General feebleness of facial structures, both cartilaginous and bony. 



7. Small Eustacliian hole, and annulus tympanicus. 



8. Absence of inter-stapedial segment, and supra-stapedial ray, with stunted extra- 

 stapedial. 



9. Modification of hyo-branchial apparatus, a. No hypo-hyal, or front lateral lobe ; 

 and I). A distinct extra-hyal, either a rudiment of the pectinate " inter-branchial " 

 of the Selachians or a remnant of the first extra-branchial of the Tadpole. 



Note — That the open ivindow in the orbital space is like what I have described in 

 another small Australian type, namely, Camariolius (" Ranidaj") (same Plate) ; it is 

 seen in a less degree in some of the small Hyke (Plate 31, fig. 7), and in the little 

 Bo7)%binator Toad [Fseudophrf/ne) (Plate 42, fig. 2) ; all from the same region. 



Second Family. "Hylodid^e." 

 First genus. Hylodes. 

 43. Ill/lodes martinicensis. — Adult female; 1^ inch long. Martinit^ue. 



This skull dlfiers in many respects from that of the Oriental " Polypedatidse ;" and 

 the species of Uijlodes evidently bear the same relation to the Cystignathine Frogs of 



