XXXV11 



(p. 00) made and those of like character, it may be said that a general 1 

 description of the skull and shoulder girdle of a cod, a perch, a mullet, a 

 pike, a salmon, or an electrical eel would almost equally well apply to the 

 one as to the other, or any other Teleostean fish, so far as the simple 

 number and essential connections of the bones are concerned. The frontal 

 bones may be single or double, the anterior sphenoid (Cuv.) may be pre- 

 sent or absent, the palatine and pterygoid bones may be distinct, or (as 

 in the electrical eel) in part fused together, the scapular arch may be 

 attached by one or two processes to the skull, a mesocoracoid may or 

 may not be persistent, and even the paraglenal bones may be quasi-car- 

 tilaginous, but the agreement in other respects is so close in contrast with 

 the representatives of other orders, that the exigencies of classification 

 seem to be best met by the union of all such in one order. In all, the 

 deviations in the skull are comparatively slight, and the scapular arch 

 is composed of a post-temporal and posterotemporal, the latter connecting 

 with the proscapula, while the paraglenal or coracoid is differentiated into at 

 least a hypercoracoid and a hypocoracoid, the latter two bearing the acti- 

 nosts which are generally four or (rarely) five in number. With the postero- 

 temporal or proscapula is connected a " postclavicle" from which is gene- 

 rally developed a second distal bone, and sometimes (in Clupeidae) several. 

 The brain, heart, and vascular system generally, and hyo-branchial appa- 

 ratus are fundamentally similar, but exhibit (especially the last) minor 

 modifications that indicate narrower differences, and that may be used in 

 the distinction of inferior groups. For all the forms possessing the common 

 characters alluded to, may be retained the ordinal name TELEOCEPHALI, 

 already referred to. 



If a typical physostome fish (e. g., Clupeid) and a specialized physoclyst 

 form (e.g., Perca, Blennius) are contrasted, the differences certainly appear 

 to be considerable, and are exhihited in (1) the presence or absence of a 

 ductus pneumaticus, (2) the position of ventrals, abdominal or anterior, (3) 

 the presence or absence of a mesocoracoid, (4) the junction of the parietals, 

 or their separation by the intervention of the supraoccipital, (5) the pre- 

 sence of articulated branching rays or their representation by spines, (6) 

 the low or comparatively high insertion of the pectoral fins, and (T) the 

 course of the lateral line, whether decurved in the direction of the abdomen 

 or curved in the direction of the back. But distinct as these forms appear 

 to be when contrasted, numerous forms intervene in which the characters 

 successively disappear, or are combined in different ways, and the most es- 

 teemed differential characters (presence or absence of the ductus pneumati- 



1 I trust that the reservations and explanations which accompany this statement, 

 and the connection iu which it occurs (the discussions of orders), maj prevent me 

 from being misunderstood. 



