472 PROCEEDINGS OF THE NATIONAL MUSEUM. vol.xxi. 



slant; upper portion twice as lonj? as lower; articulated with skull 

 by aiibclentatc sutures; entire portion below angle Joined to pterotic 

 and opisthotic; ujjper end joined broadly to cpiotic; two narrow 

 dermal bones articulated (irndy along- its anterior edge, but not bridg- 

 ing over space between it and skull i)roper. 



Supraclaviclc (so/) comparatively short, spreading out fan-like and 

 divided into three short spines. 



Clavicle (c7) very slender and long, bent at an angle at about its 

 middle; pectoral fin well below angle; about half of hypercoracoid lying 

 under it and Joined by S([uamous sutnre. 



First actinost (a) very large and long, Joined to hypocoracoid ; upper 

 three gradually growing smaller and Joined to hypercoracoid; upper 

 ray of pectoral working directly ujion hypercoracoid. 



Postclavicle (^c/) of a single piece; heavy, long, and bayonet-shaped. 



SUSPENSUIUUM, Ol'ERCLES, MAX ILI.AUIES, AND MANDIBLE. 



(IMates XXXVI, fig. 9; XXXVII, lig. 13.) 



Tho HiiHp(!iisorinin is turnod b;i(k u])oii itself. Tlie inesopterygoid bus crowded 

 itsolf ill between the (Hiiidnite aud nictiipteiygoid, still holding its attiiclimoiit with 

 tho i)teryyoid by drawing tlio upper end oitiiat bone after it and bending it around 

 the upper etui of (uiadrate, earryiug the palatine back till it is ])osterior to the man- 

 dibular articulation of the (juadrate, attaching itself to the side of the syniplectic, 

 and crowding the metapterygoid far from its usual proximity to the (juadrate. 



This crowding back of tht* suspensorium has worked in an opposite way upon the 

 opercular apparatus. The mandible in following the palatine back has swung on 

 the quadrate as a fulcrum, and thrown its long lower or posterior end (angular) 

 forward, which has drawn the opercular bones after it, elongating them and giving 

 them a general trend downward and forward. 



I'erhaps this state of affairs is all brought about by a gradual decrease in the size 

 of the skull projjor, pulling the palatine toward the hyomaudibular, and the rest 

 following as desm-ibed. 



Hyomaudibular ihm) rather elongate; its head simple without difier- 

 entiated knob; separated by a long si)ace from symi)lectic. 



Symplectic {sy) an exceedingly long, slender splint, its anterior end 

 running in a groove behind posterior third of quadrate. 



Pterygoid {pt) extending upward and backward; upi)er end turning 

 backward around quadrate. 



Mesopterygoid {mspt) articulated with symplectic posteriorly, and 

 holding on its posterior upper edge the metapterygoid. 



Metapterygoid {m2)t) very small; its ui)per end touching hyomaudib- 

 ular. 



Preopercle (po^)) a long, slender bone bent on a slight even curve. 



Opercle {op) triangular in shape, bearing 8uboi)ercle (sop) below, 

 which turns up around its anterior edge a short distance. 



Interopercle (iop) long and feather-shaped, supported by ligaments 

 only; attached to opercle and subopercle posteriorly, to angular ante- 

 riorly. 



