DEVELOPMENT OF THE SKULL IN THE BATRACHIA. 249 



first upper labial in front («./'.), and by the second upper labial {u.l~.) outside (see 

 figs. 1, 2, 3, 5 and 6). 



A little way outside the septum nasi the holes for the branches of the orbito-nasal 

 nerves (fig. 5, n.ii.) are very large and round ; outside and in front of these outlets is 

 the place for the " pro-rhinals," which are, at most, extremely feeble.'" 



The palatines (/k(.) are confluent with the ethmoid; the pterygoids (jyg.) are in 

 gi'eat contrast with them, they are very feeble, the smallest, relatively, even with their 

 cartilaginous model, that I have, as yet, seen. 



Each bone is a gently curved needle, with a groove in which the cartilage lies 

 outside and above, the point nearly touches the palatine, the " eye " is not finished by 

 bone, it is the small, oval, outwardly-turned Eustachian opening (ew.). There the bone 

 becomes forked, and the inner fork is a small foot, with a sub-convex cartilaginous 

 sole — the pedicle (pel.). The outer fork is lai-ge, it is the unossified quadrate (fig. 7, q).) 

 which passes do\\nwards and a little backwards, and ends in the large reniform condyle 

 whose direction is unusually transverse, the fore lobe being but little in advance of 

 the other. 



The annidus (fig. 3, a.ti/.) is of the normal diameter, its breadth moderate, its horns 

 sharp and open, so that the whole is but three-fifths of a circle. This very open 

 crescent is always a correlate of a small tympano-Eustachian cavity ; and these 

 may be combined, as they are here, with a very large columella ; for an over large 

 columella is ichthyic; when the metamorphosis is most complete the " epi-hyal " element 

 is arrested whilst very small, and wrought into the elegant tympanic " key." 



The stapes (figs. 3 and 7, tit.) is large and oval, but with a concave deficiency in its 

 antero-superior margin ; it has no boss. 



The columella is as large, proximally, and larger, distally, than the stapes ; the 

 inter-stapedial segment {i.st.) is as long as the stapes but has a concavity below; its 

 distal third is ossified and united by sutiu:© with the obhqnely clubbed upper end of the 

 medio-stapedial {m.st.); the staff" is no longer than the knob, and becoming cartilaginous 

 obhquely, it passes into the orbicular extra-stapedial {e.st.). This part is evenly cir- 

 cular, and its diameter is equal to the length of the stapes ; it has a supra-stapedial 

 bud (s.st.), which is short, thick, and mammillate. 



The mandible (fig. 4) is stronger than the cheek, its mento-Meckelians {m.ynk.) are 

 large, its coronoid region low, and its condyle long and cylindroidal ; the dentary ((7.) 

 is short, and neither it nor the articular {<(>:) hides more than half the ])ith (ink:). 



• This little skull was worked out two or tliree years ago, and became aceitleutally dried when m_v work 

 was nearly finished, so that I could not trace the pro-rhinals into the preniaxillaries. I have no doubt of 

 their existence ; in skulls most akin to this, such as the species of Phryniscus, they arise outside and in 

 front of the nerve-passage, and He on each side as a very fine thread of hyaline cartilage between the 

 laminae of each prcmaxillary, in a mass of connective tissue, with the point inwards as in most of the 

 toothless t3rpes. When so small aa this, they always come away with the bone when it is detached in 

 search for them ; and it ha.s to be stained and mounted for high powers — \ inch object glass — before the 

 pro-rhinals can be demonstrated. ^ \ 



MDCCCLXXXI. 2 K 



