196 UPPER CRETACEOUS TELEOSTS 
Presumably because of their similar habits, similar derivation from a salmoniform 
stock and similarity in evolutionary potential, many parallels can be drawn between 
the enchodontoids and the more advanced ‘alepisauroid’ myctophiforms (Marshall, 
1955): 
The first, and most striking, similarity between the enchodontoids and the 
advanced myctophiforms is the size and profusion of the buccal teeth. In both 
groups the dentition is concentrated on the palato-pterygoid, being absent from the 
vomer and only Enchodus showing a few scattered teeth on the endopterygoids. 
The structure of the palate, however, is somewhat different in the two groups. 
The palatine of the ‘ alepisauroids’ is extended and bears a row of large teeth, 
whereas the ectopterygoid remains short and often has no teeth (Text-figs. 78 
and 79). In the enchodontoids the palatine always bears a single terminal tooth 
and the ectopterygoid is more extensive and supports a row of large teeth. The 
end product is the same in that the palato-pterygoid is straight and bears a row of 
large ventral teeth. 
Great similarities are apparent in the structure of the dermal upper jaw, excluding 
whether the maxilla enters the gape or not. The fenestrated premaxillary pedicel in 
the enchodontoids is considered by Goody (1968 : 228) to be an enlarged articular 
process. A similar complex is seen in Lestidium and Anotopterus (Text-fig. 78) which 
both possess a true fenestrated ascending process, through which the slightly enlarged 
anterior dentary tooth projects much as in the enchodontoids. In Omosudis and 
Alepisaurus (Text-fig. 79) the premaxilla has a deep groove, rather than a discrete 
fenestra, between the narrow, attenuated ascending process and the expanded 
articular process. The maxillary head in the enchodontoids and the ‘ alepisauroids ’ 
is similar in being simple. However that of the enchodontoids would appear to be 
primitive, whereas that of Alepisaurus is derived by simplification from a more 
complex pattern seen in the basal myctophiform stock. 
Some of the smaller skull bones which are present in the basal myctophiform stock 
are lost in the more advanced members and in this respect the advanced myctophi- 
forms resemble the enchodontoids more closely. For example, the nasals become 
fused with the modified mesethmoid in ‘ alepisauroids ’ and in the enchodontoids the 
nasals are presumed to have disappeared completely. Supraorbitals and ant- 
orbitals are also absent in both groups. The basisphenoid and orbitosphenoid, 
which are both absent in the enchodontoids, are represented through all stages of 
reduction including total loss in the ‘ alepisauroids’ (Parr, 1929). Excluding the 
mesethmoid region, the neurocranial structure of Enchodus and Alepisaurus is 
somewhat similar as Goody (1968 : 229) has shown. 
In the Enchodontoidei an interoperculum is absent ; this peculiarity has also been 
observed in the suborder Cimolichthyoidei (p. 190). Several of the more advanced 
myctophiforms (Omosudis, Alepisaurus, Evermannella and Scopelarchus) have a much 
reduced interoperculum which is possibly in the process of being lost. It would 
appear that forms retaining a vertical suspensorium tend to have reduced inter- 
opercula, since presumably it no longer has a functional significance. 
Within the Enchodontidae (Palaeolycus, Text-fig. 43) there is a tendency for the 
body to become lengthened. This tendency is exhibited in the advanced ‘ alepi- 
