DEVELOPMENT OP THE SKULL IN THE BATRACHIA. 
249 
first upper labial in front ( u.l k), ancl by the second upper labial ( u.l 3 .) 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.n.) 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 (pa.) are confluent with the ethmoid ; the pterygoids (pg.) are in 
great 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 (eu.). 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 large, it is the unossified quadrate (fig. 7, sp.) 
which passes downwards 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 annulus (fig. 3, a.ty.) 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, st.) 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 suture with the obliquely clubbed upper end of the 
medio-stapedial (m.st.); the staff is no longer than the knob, and becoming cartilaginous 
obliquely, 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-stapeclial 
bud ( s.st .), which is short, thick, and mammillate. 
The mandible (fig. 4) is stronger than the cheek, its mento-Meckelians (m.mJc.) are 
large, its coronoid region low, and its condyle long and cylindroidal; the dentary (cl.) 
is short, and neither it nor the articular (ar.) hides more than half the pith (rnk.). 
* This little skull was worked out two or three years ago, and became accidentally dried when my work 
was nearly finished, so that I could not trace the pro-rhinals into the premaxillaries. I have no doubt of 
their existence ; in skulls most akin to this, such as the species of Pliryniscus, they arise outside and in 
front of the nerve-passage, and lie on each side as a very fine thread of hyaline cartilage between the 
laminae of each premaxillary, in a mass of connective tissue, with the point inwards as in most of the 
toothless types. When so small as this, they always come away with the bone when it is detached in 
search for them; and it has to be stained and mounted for high powers—j inch object glass—before the 
pro-rhinals can be demonstrated. 
MDCCCLXX X I, 2 K 
