ESPECIALLY MYCTOPHOIDS 169 
III. DISCUSSION 
This section is devoted to a discussion of the new families and suborders erected 
in the systematic descriptions (Part II). Each group is considered separately. 
Order SALMONIFORMES 
(A) Suborder ICHTHYOTRINGOIDEI 
A new suborder has been erected to contain the three genera Ichthyotringa, 
Apateodus and Apateopholis as set out in the systematic descriptions. The suborder 
has been divided into two separate but closely related families, the Ichthyotringidae 
and the new family Apateopholidae. Despite the similarities between the two 
(compare Text-figs. 3 and 15), the Apateopholidae is somewhat more advanced. 
The advanced characters form the basis of the familial division :— 
ICHTHYOTRINGIDAE APATEOPHOLIDAE 
1. Complete roof to the post-temporal fossa. Post-temporal fossa unroofed. 
2. Supratemporal present but reduced. Supratemporal absent. 
3. Orbitosphenoid present. Orbitosphenoid absent. 
4. Basisphenoid present. Basisphenoid absent. 
5. Posterior infraorbitals expanded. Infraorbitals much reduced in extent. 
6. Jaw suspension vertical. Jaw suspension forwardly inclined. 
7. No cranial deepening. Cranium deepened. 
8. Complete covering of cycloid scales. Body naked except for a row of lateral line 
scales. 
Apart from these features the two families are linked by several primitive features 
of the body and tail, and by several advanced characteristics associated with the 
production of an elongate rostral region. 
The rostrum is composed of premaxillae, maxillae, palatines, vomer and meseth- 
moid. In both families simplification has occurred by the loss of the nasals (or their 
combination with the mesethmoid) and the loss of both antorbitals and supraorbitals. 
Teeth are borne on the palatines and the premaxilla but not on the vomer. This 
rostral composition is similar to that seen in the dercetids (pp. 50-71) and certain 
of the ‘ alepisauroid myctophiforms ’ (Parr, 1929; Marshall, 1955). 
The general form of the body is the same in both families and is short, relative 
to the rostral elongation, with approximately 40 vertebrae. The anterior neural 
spines are composed of separate lateral elements ; intermuscular bones occur 
along most of the column ; the dorsal fin is in the mid-region of the back ; the anal 
fin is remote ; the pelvics are abdominal, lying below the dorsal fin ; the pectoral 
fins are set low on the flanks and consist of a large number of rays. In addition to 
these features the caudal skeleton contains two free ural vertebrae, thus corres- 
