ESPECIALLY MYCTOPHOIDS 85 
the pars jugularis is visible through this gap in the lateral wall). Vestiges of the 
narrow splint of bone forming the jugular canal are visible in 4001 (Text-fig. 38A) 
where they appear as small projections on the surface of the prootic both above and 
below the region of the jugular passage. The remainder of the trigemino-facialis 
chamber is similar in both specimens, with the trigeminal foramen opening into the 
hind wall of the orbit and not into the pars jugularis. In P.6461 a further small 
elongated foramen is seen dorso-medial to the trigeminal foramen and may have 
transmitted either the profundus or the oculomotor nerve. 
If in fact specimen P.6461 does belong to the genus Enchodus then the degeneration 
of the wall of the jugular canal and the confluence of the hyomandibular and jugular 
openings can occur within a single genus. This process has been shown by Patterson 
(1964) to be a general trend within the teleosts associated with an overall advanc- 
ment in bodily structure. 
tf 4 hm.VIl 
Il 
Il 
p.t.f.c 
f.f G.t.f.c p.t.f.c 
A. f.0.a B. 
Fic. 38. Prootic bones in antero-lateral view. (a) Enchodus lewesiensis (Mantell). 
From B.M.N.H. number 4oor. (B) Enchodus sp. From B.M.N.H. number P.646r1. 
Enchodus marchesettii (Kramberger) 
(Text-figs. 39-42) 
1895 Eurygnathus marchesettti Kramberger : 34, pl. 7, figs. 2, 2a. 
1901 Enchodus marchesettu (Kramberger) Woodward : 200. 
1903. Enchodus marchesettit (Kramberger) ; Hay : 421, pl. 30, figs. 2, 3. 
1952 Enchodus marchesettu (Kramberger) ; Arambourg : 232, fig. 50. 
DraGnosis (emended). Enchodus species of standard length not exceeding 18 cm. 
The length of the head only just greater than the depth at the occiput, and just less 
than the maximum depth of the body. Head with opercular apparatus equal to one- 
third of the standard length. Mandible long and deep, its maximum depth being 
less than one-third of its total length. Teeth much smaller than in the type species. 
Maxilla thin and toothless. Operculum almost twice as deep as broad ;_ sub- 
operculum very deep. Dorsal fin consisting of 16 rays ; anal fin with 20 rays and 
