DEVELOPMENT OF THE SKULL IN THE 13ATRACHIA. 61 



*fig. 8, 2).rh.)nYe well developed, but there is a small prenasal rostrum; tlie bulbous end 

 of septum nasi is somewhat emarginate. The fore part of the palato-suspensorial car- 

 tilage is thick, and foi'ms a triangular pre-palatine ; its nan-ow ethmo-palatine pedicle 

 has on its postero-inferior surface a slight palatine ossification (pa). Tliis cartilage 

 in its pterygoid, quadrate, and auditory regions, is slender ; the pterygoid bone (pff-) is, 

 however, well-developed — not like that of a young Frog — and only leaves the upper 

 and outer surface of the cartilage naked (fig. 7). Each pedicle (pt?.) is small, and 

 they are wide apart; so also is the quadrate region, but it ends in u large condyle 

 {(j[.c.) that reaches as far backwards as to the middle of the stapes ; this is quite an 

 average retreat backwards. The Eustachian openings (eu.) are of medium size, oval, 

 and transverse, and the space of the middle ear is well developed. 



The anniilus {a.ty.) is large, and its hoi'ns neai-ly meet; the stapes (fig. 11, at.) is 

 large and oval, with a moderate anterior scooping for the columella. 



This rod is well ossified in its main part, and has no appearance of belonging to a 

 young individual ; its interstapedial segment (^i.st.) is small, pisiform, and lies between 

 the large unossified lobes of the long, arcuate medio-stapedial {ni.st., m.st'.). The extra- 

 stapedial (e.st.) is a small, long-oval lobe of cartilage, and has no supra-stapedial process. 

 The mandil)le (fig. 9) is quite normal. The styloid end of the hyoid bar (st.h.) is 

 articulated with the ear-capsule; the bar itself (fig. 10, c.hy.) is narrow, and has no 

 hypo-hyal lobe ; the two side lobes of the basal plate (h.h.hr) are small ; the thyro- 

 hyals {t.hy.) are noi-mal. 



The narial valves (fig. 12, ti.l^.ii.I'-.) are well developed and perfectly normal. 



The investing bones lend no support to the opinion that this is anything but a 

 mature individual : they are well developed ; those on the upper surface difi^er from 

 their counterparts in a full-grown Common Frog, by the nasals (n.) being relatively 

 much larger and nearer together, and the fronto-parletals {/.j)-) completely anchylosed 

 along the middle — all save their pointed front ends, where a little of the fontanelle 

 (fo.) is exposed. This common sheet of bone well covers the roof behind, and 

 although the bone is thin, it is highly developed as bone tissue. 



The nasals («.) touch the septum nasi (s.n.) and curving elegantly outwards in 

 front, overlie the large sub- tubular external nostrils (e.n.) which are very wide apart. 



The fore part of the endocranium is well wrapped in the nasals, the pre-maxillaries 

 (px.) und the maxillaries (mx.) ; these outer bones are but little developed in the 

 palatine region, but are large and foliaceous on the outside. 



The jugal pai't of the maxillary is joined to a quadrato-jugul ('/.,/.) wluL-h is well 

 grafted on to the quadrate : a good sign of maturity. 



The upper part of the squamosal (sq.) is narrow, but all its regions are well 

 developed. 



The parasphenoid (fig. 8, 2M.s.) is well developed and large, but is not so elegant as 

 in the Common Frog, its angles behind being attenuated and not outspread ; the 

 vomers (v.) are small crescents, widest in front and forming ;\ mere lK)ok behind ; 



