20 U.S. NATIONAL MUSEUM BULLETIN 2 84 



lateralmost extension of each lateral ethmoid forms a syndesmotic 

 joint with the broad dorsal surface of its respective lachrymal (first 

 circumorbital). Ventrally and mesially there is an enlarged condyle 

 on each lateral ethmoid that articulates with the dorsomesial surface 

 of its respective palatine bone. This connection is a diarthrosis (see 

 Thiele, 1963, for Blennius). 



There is a thin, median, cartilaginous, and membranous inter- 

 orbital septum that attaches to the posterior surface of the lateral 

 ethmoids, the anteroventral surface of the frontals, the anterodorsal 

 surface of the parasphenoid, and includes the anterior end (belophram, 

 see p. 43) of the basisphenoid. 



Vomer (figs. 1, 2, 4). — Viewed dorsally or ventrally the vomer is a 

 T-shaped bone with the cross arm (head) of the T anterior. Ventrally 

 the head of the vomer bears a row of conical teeth. Dorsally each 

 side of the vomerine head bears thin, ascending, irregular processes 

 that join with the lateral ethmoids. The processes surround a median 

 depression in the vomer that contains the ethmoid cartUage. For 

 most of its length the posterior process of the vomer is overlapped 

 on either side by thin anteriorly extending blades of the parasphenoid. 



Parasphenoid (figs. 1, 2, 4). — The median, ventrally keeled para- 

 sphenoid externally overlaps each side of the vomer anteriorly. On 

 each side, at about its midlength, the parasphenoid gives rise to 

 broad ascending processes, each of which meets its respective frontal 

 dorsally, impinges slightly on the lateral margin of the basisphenoid 

 and broadly on the ventral external surface of its respective ptero- 

 sphenoid and the anteroventral portion of its respective prootic. 

 Posterior to the ascending processes on each side, the parasphenoid 

 joins its respective prootic for most of the prootic's ventral margin. 

 The posterior end of the parasphenoid is joined and overlapped on 

 either side by the median basioccipital. 



On each side, somewhat posterior to the anterior end of the para- 

 sphenoid and extending just anterior to the origin of each ascending 

 process, the parasphenoid bears dorsally a narrow ventrolaterally 

 directed sheK. This shelf, as well as the remaining ventrolateral 

 surface of the parasphenoid on each side, gives rise to a broad sheet 

 of connective tissue that attaches to the mesopterygoid and meta- 

 pterygoid. 



Basioccipital (figs. 2-5). — The basioccipital is roughly rectangular 

 in ventral (and dorsal) aspect. There is a deep, slender notch in the 

 median anterior portion of the bone. Anteroventrally and medianly 

 the basioccipital is overlapped by the parasphenoid and appears 

 roughly V-shaped in ventral aspect. The posterior portion of the 

 basioccipital is thickened and expanded into a large circular condyle, 

 which articulates with the centrum of the first vertebra. Dorso- 



