FISHERY BULLETIN; VOL. 79, NO. 3 



Pterotic 



PterosphenoiiJ 



Parasphenoid 



Exoccipital 



Vomer , 



22nd pre-ural 

 centrum 



Basioccipital 



Lateral ethmoid 



Figure 5. — Ventral view of cranium of Tetrahrachnim 

 ocellatum. AMS IB.7178, 61 mm SL. 



Frontal 



Sphenotic 



Posttemporal 



Supraethmoid 



Frontal 



Lateral 

 ethmoid 



Sphenotic 



FIGURE 6. 



Vomer 



-Anterior view of cranium of Tetrahrachium ocel- 

 latum, AMS IB.7178, 61 mm SL. 



The frontals are relatively large and irregular 

 in shape. Each has a laterally compressed, ante- 

 rior half, well separated from its counterpart of 

 the other side, and a dorsoventrally depressed 

 posterior half that meets its counterpart on the 

 midline. In dorsal view (Figure 3), the frontals 

 form a relatively narrow orbital region to accom- 

 modate the closely set, dorsally directed eyes. In 

 lateral view (Figure 4), the depressed posterior 

 half of the frontals form a concavity between the 

 elevated, laterally compressed anterior half of 

 these bones and the posterior half of the cranium. 



The parietals are irregularly shaped elements 

 with deeply pitted and grooved external surfaces. 

 They are well separated from each other by the 

 supraoccipital. Each parietal overlaps the respec- 

 tive frontal anteriorly, the sphenotic and pterotic 



laterally, the supraoccipital medially, and the 

 epiotic posteriorly. 



A small pterosphenoid lies on the ventromedial 

 surface of the frontal in contact with the prootic. 



The orbitosphenoid and basisphenoid are absent 

 in all lophiiforms. 



The parasphenoid is a stout, well-ossified ele- 

 ment with a convex ventral margin (Figure 4). Its 

 anterior end is overlapped by the ethmoid carti- 

 lage dorsally and by the narrow shaft of the vomer 

 ventrally. Medially, the dorsal surface of this bone 

 forms a deep groove within which lies the laterally 

 compressed, posteroventral part of the supra- 

 ethmoid. Posteriorly, the parasphenoid is broadly 

 connected with the prootics laterally and the 

 basioccipital medially At no point does the para- 

 sphenoid make contact with the frontals. 



Each sphenotic forms a dorsoventrally de- 

 pressed flange that extends outward in an antero- 

 lateral direction, considerably beyond the width 

 of the ethmovomerine region of the cranium 

 (Figure 3). 



The remaining elements of the cranium (pterot- 

 ics, epiotics, prootics, supraoccipital, and exoccip- 

 itals) do not differ substantially from those de- 

 scribed for other lophiiforms (Regan 1912, fig. 5; 

 Gregory 1933, fig. 265, 267-271; Pietsch 1972, 

 1974). 



Otoliths (Figure 7).— The sagitta of T. ocellatum 

 is roughly oval in shape with a length to height 

 ratio of about 1.4:1. The sulcus is only slightly 



392 



