| OCR Text |
Show 1895.] HYOID BONE OE CEETAIN PABBOTS. 169 slender than in P. erithacus. It is also more curved, concave downwards, and presents a lateral sigmoid flexure, the anterior curve whereof is convex outwards, while the more distal one is convex mesiad. It also expands slightly more transversely at its distal end. The ceratobranchial is much like that of P. erithacus, but slightly less expanded laterally and a little more curved, concave mesiad. LOEITJS ELAVOPALLIATUS. (Fig. 3, p. 168.) The hyoid of Lorius fiavopalliatus agrees with that of Lorius domicella except in the following few particulars. The basihyal is more strongly and sharply bent dorsad towards its preaxial end. Tbe two lateral halves of its posterior margin form a more decided angle with each other, open forwards. Each postero-external margin of the basihyal plate forms a much more marked and smaller angle with the proximal part of tbe crus of the parahyal arch. The crura of the arch are somewhat shorter, its symphysis being much longer and more pointed. The symphysis curves, antero-posteriorly, more strongly concave downwards. The entoglossumhas its constituent halves divergingmorepreaxiad. Seen laterally the anterior end of each entoglossal develops three short, vertically superimposed marginal processes. The urohyal is not so much bent ventrad towards its distal end. The hypobranchial is relatively slightly shorter. The ceratobranchial is less curved. EOS EETICTJLATA. (Fig. 4, p. 170.) Basihyal-This bone in Eos reticulata has its expanded posterior part intermediate in form between those of Lorius domicella and Lorius fiavopalliatus. The angle formed by the two sides of its posterior margin is more like that in the former, while the shape of its external margins (behind the origins of the crura of the parahyal arch) are more like those of L. fiavopalliatus. The crura are rather shorter than in either of those species, though the symphysis of the arch is elongate, but not so much so as in tbe last-named species. The dorsal cup-like excavation at the preaxial end of the bone is as marked as in either of the before described forms. The urohyed is very short and bent ventrad at its distal end as in L. domicella. The entoglossum has its two lateral parts not so much diverging preaxiad as in L. fiavopalliatus. The cartilage joining them anteriorly is medianly notched in front and somewhat medianly prolonged behind. Both the lateral processes of each entoglossal are well developed. The hypobranchials are relatively shorter and stouter than in Lorius, but with a similar sigmoid flexure. |
