REPORT ON THE GREEN TURTLE. 37 



Further outwards one Batracliiau character is effaced, for the "extrastapedial" (e.st.) has 

 lost its segmentation from the mediostapedial rod ; yet it has become perfectly like that 

 of several of the Batrachia in form, for the distal plate is quite circular, and there is a 

 short suprastapedial process (s.st.) arising, from it. (See Batrachia, pai't 2, Phil. Trans., 

 1876, pis. liv., lix., and Ixii.) 



I must refer, also, to the same paper to show how Batrachian the rest of the outer ear 

 is, for here we have the old cartilaginous annulus tympanicus (figs. 2, 10, a.ty.) ; this 

 cartilage, like the sheath of the notochord and the stapedial plate, is composed of flat 

 cells, but is truly cartilaginous. It is a nearly perfect oval, the gap being postero- 

 inferior in position, and occupied by the distal part of the columella ; postero-superiorly, 

 it has a large, crescentric, concave " flange," imitating the concave part of the " otic pro- 

 cess" of the quadrate (fig. 7). Fitting fairly into that part, the annulus serves for the 

 attachment of the " membrana tympani " {m.ty.) many of the fibres of which are inserted 

 into the convex outer face of the " extrastapedial." The suprastapedial process, which is 

 directed obliquely backwards, is embedded in a thick ligamentous mass, to which the 

 fibres of the short, thick, " stapedius muscle" are attached. 



These structures of the "middle ear" come much closer to those of the Batrachian, 

 and resemble those of the Bird much less, than the corresponding parts do in Lacerta 

 agilis and the higher " Lacertilia " generally. 



The inferior free arches (figs. 1, 2, and 6) are also very Batrachian; but the mandibles 

 [mh.) are fused together in front ; they form a cylindroidal condyle in the articular 

 region. The cerato-hyals (c.hy.) are long, sigmoid, terete rods, much ossified distally ; 

 they are quite distinct below from the " hypo-hyals" [h.hy.). which are short unossified 

 rods set on in front of them on the widest part of the basal plate. 



The basal plate, " basi-hyo-branchial" {b.hy.,b.hr.), has a lingual process, it then is 

 wide, narrower, and is widened again, terminally, where it gives off two short "horns" or 

 diverging processes, these, moreover, have articulated to them a pair of thick, shortish, 

 inbent, " hypo-branchials" or thyro-hyals (h.hr.). 



(6.) The "Investing bones" are of great interest; they are all present now, but in the last 

 stage they were mere granular tracts. Above (fig. 4), there is still a large "foutanelle" (fo.), 

 for the frontals {/.) diverge behind, and the parietals (j).) are mere lunules of thin bone, 

 as seen from the surface. Within (fig. 1), the frontals have a considerable orbital plate, 

 and the parietals have developed their peculiarly Chelonian wall to the alisphenoidal 

 region ; this descending part rests upon the epipterygoid process and pterygoid bone 

 (figs. 1, 2, 7, p.,e.2)g.,2og.) ; thus the cartilage is aborted. In front (figs. 1, 2, 4), the 

 nasals and prefrontals are in one piece {pf.n.). This prefronto-nasal is foreshadowed in 

 the huge nasal of the Batrachia, where there is no distinct prefrontal ; in them the bone 

 lacks the ingrowing antorbital plate. Here there is a considerable antorbital plate, 

 flanking that of the frontal (fig. 2), and the lachrymal space lies between it, the maxillary, 



