i6 4 ELOPIFORM FISHES 



completely to enclose the scapular foramen ; and, finally, the anterior edge of the 

 mesocoracoid fits tightly against the inflected margin of the cleithrum. The ventral 

 end of the mesocoracoid is bifurcated, producing a foramen between the mesocoracoid 

 and the coracoid. As in other parts of the skeleton the pectoral girdle of A . vulfies 

 is more extensively ossified than that of Pterothrissus. 



There are three postcleithra, the lowermost having a characteristic shape (Text- 

 fig. 82). 



The disposition, size and shape of the pectoral radials is similar to that described 

 for Pterothrissus. There are 16-17 pectoral fin-rays of which all except the outermost 

 are branched. A triangular pectoral splint is associated with the outermost ray. 



The pelvic fin arises beneath the posterior half of the dorsal fin and is supported 

 by a triangular pelvic bone. Anteriorly the pelvic bone is thin, but posteriorly it 

 becomes considerably thicker and the hind margin is capped by cartilage with which 

 the pelvic rays articulate. Medially, the base of the pelvic bone is produced as an 

 ' ischial process '. There are 10 pelvic fin-rays, the outermost unbranched. As- 

 sociated with the upper half of the first ray is a long splint bone, the proximal end 

 of which is curved sharply upwards. Whitehead (1963 : 744, fig. 3a) shows the pelvic 

 splint to be a double structure composed of an upper and lower portion. I could 

 not find any convincing example of such a double structure in any B.M.N.H. 

 specimen. 



Median fins. The dorsal is situated nearer to the occiput than to the caudal 

 peduncle and is composed of 17-18 rays, the anterior five of which are unbranched. 

 The fin is supported by 15-16 pterygiophores. In older specimens successive ptery- 

 giophores appear to be fused distally. 



The small anal fin is remote and composed of nine rays (occasionally eight) 

 supported upon seven pterygiophores. Like the pterygiophores of the dorsal fin, 

 the distal extremities may become fused in older specimens. 



Vertebral column. The only complete vertebral count available to me (B.M.N.H. 

 83. 12. 15. 106) showed 67 vertebrae of which 23 are caudal. Hildebrand (1963 : 134) 

 gives the range of vertebral counts for the western North Atlantic forms as 72-74. 

 All centra except the first 17 are as deep as long, the exceptional centra being deeper 

 than long. Each centrum is marked laterally by a stout horizontal bar flanked by 

 deep grooves. The centra bear deep pits dorsally and ventrally for the reception of 

 neural arches and parapophyses or haemal arches respectively. 



The bases of the neural arches are produced anteriorly and posteriorly forming 

 small zygapophyses. The first 31 neural arches and spines remain distinct from their 

 fellows of the opposite side and bear separate neural spines. Thus these vertebrae 

 show a double neural spine. 



The parapophyses of the first 44 centra show an elongate area which is inclined 

 antero-ventrally and serves, with a facet on the centrum, for the articulation of the 

 pleural rib. The posterior 12 parapophyses gradually increase in length and support 

 a series of progressively shorter pleural ribs. 



The neural and haemal spines of the caudal region are short. Those associated 

 with the posterior centra are expanded in the sagittal plane and aid in supporting 

 the caudal fin-rays. Preceding the first dorsal pterygiophore there is a series of 



