ESPECIALLY MYCTOPHOIDS 159 
The caudal skeleton (Text-fig. 72) consists of seven vertebrae. Four free preural 
vertebrae are present. Preural vertebra 1 is fused with ural vertebra 1, and the 
second ural vertebra is present as a terminal half-centrum. Preural vertebrae 3, 
4 and 5 bear slightly elongated neural and haemal spines which are somewhat 
expanded. Preural vertebra 2 (the first free preural vertebra) has an expanded 
haemal spine and no neural spine, but the neural arch is enlarged. The fused 
preural and ural vertebra bears the parhypural and the first two hypurals ventrally. 
Hypural 1 is larger than hypural 2, the latter not extending to the mid-line of the 
caudal fin. The second ural vertebra supports the upper four hypurals. The lower 
hy6 
Fic. 72. Sardinioides minimus (Agassiz). Caudal fin skeleton in lateral view. 
edge of hypural 3 does not reach the mid-line of the caudal fin, and thus there is a 
small gap left between the upper and lower hypural elements. The fused preural 
and ural centrum bears an enlarged, anteriorly expanded stegural. This is inclined 
postero-dorsally and a second uroneural is present behind it. Three epurals 
associate with the dorsal edge of the anterior expansion of the stegural. 
The caudal fin consists of 19 principal rays of which 17 are branched. Ten 
accessory rays occur epaxially and 10 hypaxially. In front of the anteriormost 
accessory ray, both dorsally and ventrally, is an enlarged fulcral scale. 
Scales. The entire body is covered with cycloid scales which extend on to the 
opercular bones. Scales also cover the cheek region, the posterior end of the 
maxilla, the articular region of the mandible, and extend on to the dorsal surface of 
the skull as far as the centre of the orbit. In the smaller specimens the scales are 
strictly cycloid, but in larger specimens the scales may become very feebly ctenoid. 
