70S DR RAMSAY H. TRAQUAIR's DESCRIPTION OF 



sketch of the various bones which I have been able to distinguish. On looking 

 at fig. 10, the first thing which strikes the eye is the nearly exact resemblance pre- 

 sented by the outlines of the bones to those in Pygopterus, if we take the above 

 described P. Greenockii as an example of the genus. Of the bones of the 

 shoulder-girdle, the suprascapular (50) is readily distinguished as a triangular, 

 somewhat convex, plate at the hinder part of the skull above the operculum. To 

 this succeeds the elongated scapula (51), and then the coracoid (52), which, as in 

 Pygopterus, forms an angle at the pectoral fin where it bends inwards on the 

 under surface of the throat towards its fellow of the opposite side. We have 

 also the triangular pre-coracoid plate, which, meeting in the middle line with its 

 fellow of the opposite side, forms with it a pointed process, passing forwards the 

 two lateral series of branchiostegal plates (44). 



The opercular apparatus is conformed as in Pygopterus Greenockii, the opercu- 

 lum (35) being narrow and of an oblong rhomboidal shape, the suboperculum 

 (36) nearly square ; while the same difficulty is experienced in finding a distinct 

 pre- and sub-operculum, so that those bones, if present, must have been very nar- 

 row. The superior maxillary bone (21), though not so strong as in Pygopterus, has 

 essentially the same form, consisting of a stout oblong plate, its posterior margin 

 sloping downwards and backwards, and its superior margin beveled off in a 

 semilunar manner below and behind the orbit. The lower jaw (L, J) is stout, and 

 beautifully tapering from its posterior articular extremity towards the symphysis ; 

 the gape extends very far back ; the teeth in both jaws are minute, and only to 

 be studied by means of a lens ; then they are seen to be smooth, and of an acutely- 

 pointed slender-conical form. The branchiostegal plates (44, fig. 11) are fourteen 

 on each side, with an azygos one in the middle, immediately behind the symphysis 

 of the lower jaw. The azygos plate, and the anterior one of the lateral series on 

 each side, are of a rhomboidal form ; the rest are more narrow, oblong plates, with 

 the hinder margin rather broader than the front. They seem also to be slightly 

 shorter in the middle than at each end of the series. At the lower and posterior 

 border of the orbit may always be seen a sickle-shaped suborbital (73), and the 

 examination of some specimens, a little better preserved than others, leads me to 

 the conclusion that the eye was completely encircled by a chain of similar ossicles, 

 but which, however, from the crushing to which the heads have been subjected, 

 cannot be counted or definitely sketched. Behind the orbit, and above the upper 

 jaw-bone, are also one or more plates covering the cheek. 



Owing to the crushed state in which the heads of the smaller fishes occur, I 

 have no specimen in my collection which shows the bones of the cranial shield 

 so beautifully as they are displayed in the head of Pygopterus, figured Plate XLV., 

 figs. 2, 3, 4. The examination of several specimens in a better or worse state of 

 preservation shows, however, that their cranial bones were essentially similar to 

 those of the last-named fish, the whole cranial shield being apparently a little 



