ESPECIALLY MYCTOPHOIDS 107 
scapular foramen is, however, visible. Four small hour-glass shaped radial bones 
are present on the posterior edge of the scapulocoracoid and with these the 13 rays 
of the pectoral fin articulated. The first ray is the longest, the rest gradually decreas- 
ing in size. Due to the posterior expansion of the cleithrum, the pectoral fin is raised 
slightly so that its point of insertion has moved up the flank. 
A small, narrow and curved postcleithral bone attaches to the postero-ventral part 
of the supracleithrum and projects postero-ventrally, lying medial to the radial 
elements of the pectoral fin. 
Pelvic girdle and fin. Each pelvic bone is composed of a roughly triangular sheet 
of thin bone which is flattened and meets its partner in the mid-ventral line just 
posterior to the cleithrum. The pelvic bones therefore can be said to be sub-thoracic 
in position. Each bone bears a thickened condylar region posteriorly which lies 
lateral to an articulatory facet. The condyle is supported by a ridge passing 
anteriorly along the lateral edge of the bone. The pelvic fin consists of 8 stout rays 
all of which are branched distally and segmented. 
Median fins and tail. The median fins are shown in the restoration, Text-figure 47. 
The dorsal fin is somewhat deeper than long and contains 12 rays. The first ray is 
shorter than the subsequent ones and segmented but not branched. The elongated 
proximal radials are prominent and all are expanded to a certain extent, especially 
the first which bears a large median keel projecting anteriorly. The distal ends of 
the proximal radials are expanded at the bases of the fin rays and the medial radials 
extend obliquely between the bases of adjacent fin rays. 
The anal fin consists of 13 or 14 rays. The first ray is shorter than the second and 
is unbranched : the remainder are all branched. All the rays are segmented. The 
pterygiophore composition of the anal fin parallels that of the dorsal fin except that 
the proximal radial at the anterior end is not expanded. 
There are six vertebrae entering into the composition of the caudal skeleton 
(Text-fig. 48), three free preural vertebrae, one free ural vertebra, and a compound 
vertebra formed from the fusion of the first preural vertebra and the first ural 
vertebra. Preural vertebrae 3 and 4 both bear normal neural spines, which are 
strongly inclined posteriorly, and ventrally these preurals bear expanded haemal 
spines. Preural vertebra 2 (the first free preural vertebra), bears a greatly expanded 
haemal spine ventrally but does not possess a neural spine, simply an enlarged neural 
arch. The compound vertebra formed from the fusion of preural vertebra I with 
ural vertebra 1 bears a parhypural ventrally (the haemal spine of the first preural 
vertebra), and two hypurals which extend dorsally to the mid-line. The ventral- 
most hypural (hypural 1) is by far the larger of the two and has an oval foramen 
near to its base. Dorsally the compound centrum bears an expanded stegural 
which extends as a rod-like structure in a postero-dorsal direction, and has a thin 
anterior projection in the mid-line which extends forwards towards the neural 
arch of preural vertebra 2. The second ural vertebra is in the form of a small half- 
centrum which bears a posterior fan of four hypurals supporting the upper lobe 
of the caudal fin. The second ural vertebra also appears to bear a second uroneural 
element closely associated with the posterior edge of the stegural. At least one 
