ANATOMY OF VERTEBRATES. 125 



separates below the two branchial apertures. In the Conger the 

 hyoidean arch is simplified by the persistent ligamentous state of 

 the stylohyal, and by the confluence of the basihyals with the 

 ceratohyals ; a long glossohyal is articulated to the upper part of 

 the ligamentous symphysis, and a long compressed urohyal to the 

 under part of the same junction of the hyoid arch. The glosso- 

 hyal is wanting in the Muramophis. 



The Diverging Appendage of the hyoidean arch retains the form 

 of simple, elongated, slender, slightly curved rays, articulated to 

 depressions in the outer and posterior margins of the epi- and 

 cerato-hyals : they are called c branchiostegals,' or gill-cover rays, 

 fig. 85, 44, because they support the membrane which closes 

 externally the branchial chamber. The number of these rays 

 varies, and their presence is not constant even in the bony Fishes : 

 there are but three broad and flat rays in the Carp ; whilst the 

 clupeoid Elops has more than thirty rays in each gill-cover : the 

 most common number is seven, as in the Cod, fig. 75, 44. They 

 are of enormous length in the Angler, and serve to support the 

 membrane which is developed to form a great receptacle on each 

 side of the head of that singular fish. 



The fourth cranial inverted arch, fig. 81, 50 — 52, H, is that 

 which is attached to the paroccipital ; or to the paroccipital and 

 mastoid ; or, as in the Cod, to the paroccipital and petrosal ; or 

 as in the Perch, fig. 85, 50, and Shad, to the paroccipital and 

 basioccipital : thus either wholly or in part to the parapophysis 

 of the occipital vertebra, of which it is essentially the hsemal 

 arch ; it is usually termed the ' scapular arch.' In the Eel tribe, 

 where it is very feebly developed, and sometimes devoid of any 

 diverging appendage, it is loosely suspended behind the skull ; 

 and in the Plagiostomes, fig. 30, si, 52, it is not directly 

 attached to its proper vertebra, the occiput, but is removed 

 further back, where we shall usually find it displaced in higher 

 Vertebrates, in order to allow of greater freedom to the move- 

 ments of the head. 



The superior piece of the arch, 'supra-scapular,' figs. 81, 85, 

 50, is bifurcate in the Cod, or consists of two short columnar 

 bones, attached anteriorly, the one to the paroccipital, the other 

 and shorter piece to the petrosal, and coalescing posteriorly at an 

 acute angle, to form a slightly expanded disk, from which the 

 second piece of the arch is suspended vertically. This piece, 

 called ' scapula,' ib. 51, is a slender, straight bone, terminating in 

 a point below, and mortised into a groove on the upper and outer 

 side of the lower and principal bone of the scapular arch. The 



