58 
MR. W. K. PARKER OK THE STRUCTURE AND 
The middle and outer ears (Plate 8, figs. 1-4, and Plate 9, figs. 8-14) are in a high 
state of development; externally, the annulus ( a.ty.) is almost an inch across, and is 
complete; its greatest width, below, is fully a quarter of an inch ; it is thick-rimmed, 
unusually wide at the junction of its “horns,” and altogether unique in size and 
finish. 
The “ columella ” also is unique as to its development, having an osseous shaft in its 
extra-stapedial (Plate 9, figs. 8, 9, 10, e.st., e.st'.), which is not seen in other Batrachia. 
The stapes and the dorsal part of the columella lie in a deep hollow, in the hinder 
part of which is the fenestra ovalis (Plate 9, fig. 8). The stapes (st.) is oval, obliquely 
truncate in front, and thick and convex externally. 
Against it, and somewhat within, lies the thick, short inter-stapedial ( i.st .), whose 
distal half is bony; it is quite segmented from the medio-stapedial ( m.st.) which is 
long, phalangiform, thick proximally where it is not quite ossified, and narrow and 
arcuate further forwards. Then comes a short cartilaginous tract which is followed by 
the extra-stapedial (e.st.) whose proximal part is ossified as a styloform shaft bone 
(e.st'.), the cartilage within being also considerably ossified beyond the ectosteal tract. 
On the inner side, near the dilated end the supra-stapedial (s.st.) is given off at a 
sharp angle, it passes upwards and backwards and is confluent with the cartilage lining 
the tegmen tympani; it is nearly as broad as the main bar, and is entirely unossified. 
This division of the columella into three segments is of great interest, and can be 
understood only by comparison with the state of things seen in the upper hyoid region 
of Fishes in various groups. 
In the Chimaeroids (see Hubrecht, fig. 2, hy".) there is a “ pharyngo-hyal ” above 
the “ epi-hyal ” (hy'.), but this topmost piece, so constant in the branchial arches, 
proper, is not found in the hyoid of other Fishes. Much lower down, towards its 
distal end, the epi-hyal (“ hyomandibular ”) is cut off as a short distinct cartilage in 
the Sturgeon and Paddle-Fish. 
In osseous Fishes this cartilage acquires an additional bony sheath;—the “symplectic” 
-—but is not cut off. 
I am now jcerfectly satisfied that this lower subdivision of the “ epi-hyal” element is 
a secondary segmentation, such as is seen in the “ pharyngo-branchials” of the 
Sturgeon, where each cartilage is sub-divided into two pieces.* 
In illustration of this we see that the “ hypo-hyal” of osseous Fishes has tiro bony 
centres; in the Menopome it breaks up into three patches of cartilage. 
Therefore we see that the middle ear of this Frog has parts that correspond to the 
following morphological elements of the upper part of the hyoid arch in the Fishes :— 
1. Pharyngo-hyal=inter-stapedial. 
2. Epi-hyal, subdivided into— a, hyo-mandibular=medio-stapedial; and h, sym- 
pletic = extra-sta pedial. 
* Mr. Howes pointed out this to ine, as shown in his excellent dissections at South Kensington. 
