140 UPPER CRETACEOUS TELEOSTS 
its basal region. The remaining rays are branched but unornamented. The 
anteriormost radial is expanded into a large anterior keel. The remainder of the 
radials are unexpanded. 
The anal fin is small and remote with 9 feeble rays. The first ray is unbranched 
and unornamented and none of the radials is expanded. 
The caudal skeleton (Text-fig. 64) is made up of six vertebrae, four preural 
vertebrae and two ural vertebrae. Preural vertebrae 3 and 4 bear normal neural 
and haemal spines, although the latter are somewhat expanded. The neural and 
haemal spines of these preural vertebrae support the accessory rays of the caudal 
fin. Preural vertebra 2 does not possess a neural spine, simply an expanded neural 
arch. Preural vertebra 1 and ural vertebra I are fused together to produce a 
compound centrum. The haemal spine of preural vertebra 1 (the parhypural), 
and the first two hypural elements articulate with the ventral edge of this compound 
centrum. Ural vertebra 2 is present as a small centrum supporting the hypurals 
of the upper lobe of the caudal fin, of which there are at least three. A large rod- 
like uroneural, inclined postero-dorsally, is associated with the dorso-lateral parts 
of both the ural vertebrae. The uroneural appears to be expanded anteriorly in 
the mid-line above the first preural vertebra, and is considered to be a stegural. 
A single epural is visible above the anterior expansion of the uroneural. 
The caudal fin consists of 17 branched principal fin rays, together with at least 
16 accessory fin rays. 
Scales. The entire body is covered with a uniform coat of thin, minute scales. 
The scales along the course of the lateral line are enlarged and bear a posteriorly 
directed spine from the lateral face. The lateral line scales become progressively 
larger towards the caudal fin and on the caudal peduncle are irregular in shape with 
an enormous spine. 
Genus PHYLACTOCEPHALUS Davis, 1887 
DiaGnosis (emended). Halecidae in which the head is short but deepened ; 
body also shortened and deepened. Jaw suspensorium vertical. Supraorbital 
absent. Approximately 10 branchiostegal rays. Vertebrae 32 in number. 
Dorsal fin in second quarter of the back. Pelvics sub-thoracic, larger than pectorals. 
Epineurals on the first 19 vertebrae. Complete covering of minute scales, enlarged 
along the lateral line. 
Type spEcIES. Phylactocephalus microlepis Davis. 
REMARKS. This genus was erected by Davis (1887) but subsequently Woodward 
(1901 : 218) synonymised it with Halec. There are sufficient differences to warrant 
separation into two distinct genera and the original generic name of Phylactocephalus 
is re-erected. 
