191] OSTEOLOGY OF LORICATI—GUTBERLET 21 



SCORPIONICHTHYS MARMORATUS 



The Cranium 



The skull (Figs. 2, 5) of Scorpionichthys differs from that of 

 Ophidon only in a few points. The dorsal surface is somewhat more 

 rounded and is covered with a granulated network. The temporal 

 fossae are slightly different in shape and the orbits are smaller and 

 more circular in outline, also the surface between them is narrower and 

 concave. On the dorsal surface of the ethmoid the longitudinal groove, 

 present in Ophidon, does not occur and a large erect process extending 

 antero-laterally from the median line takes the place of the small 

 ethmoid processes. There is a broad flange on the posterior end of the 

 skull extending mesad from the caudal end of the epiotic ridge toward 

 the median line, also the supra-occipital possesses a crest on the posterior 

 surface extending from the dorsal edge to the end of the postero-ventral 

 process. The anterior end of the temporal fossa is formed mainly by 

 the edges of the granulated network of the parietals and pterotic. The 

 parietal projects over the fossa for a distance as also does the epiotic 

 which goes to make up a part of the mesial edge of the roof. Most of 

 the roof is formed by the extra-scapular lying on the dorsal surfaces 

 of the epiotic and pterotic across the fossa. In the dilatator fossa the 

 sphenotic forms the greater part of the roof, in contrast to the condition 

 in Ophidon; also there are no foramina in the fossa for the passage of 

 the branches of the otic vessels. 



The vomer (Figs. 2, 5 v) is relatively smaller than in Ophidon but 

 has the same general shape except that the lateral expansions are not 

 as long and the dorsal process is shorter. Only villiform teeth are pres- 

 ent; they are numerous and irregularly arranged. The dorso-anterior 

 surface, slightly lateral to the median line, possesses a small articular 

 facet for the articulation with a similar facet on the mesial edge of the 

 maxilla. 



The ethmoid (Figs. 2, 5, eth) has no depression on its lateral sur- 

 faces for the nasal pit. A tall antero-lateral process forms a V-shaped 

 crest in the median line, supporting the nasal bones which roof the pit. 



The prefrontals (Figs. 2, 5, pfr) are relatively large, especially 

 anteriorly; they lack depressions for the nasal pits. A thin flange 

 extends ventro-caudad from the ventral surface of the lateral edge of 

 the wing-like expansions to the mesial portion where it unites with the 

 parasphenoid in the median line. On the lateral edge of the anterior 

 portion, directly posterior to the vomer and anterior to the wing, there 

 is a small facet for the articulation with the palatine. 



