LEIOGNATHUS 15 



The baseosts are not evident at the bases of the anal and dorsal spines 

 probably becoming co-ossified with the interspinous bones. An auxil- 

 liary interneural is in front of the first spine-bearing interneural. 



There are ten abdominal and fourteen caudal vertebrae, including 

 the hypural. 



Anteriorly the neural processes are wide nearly as wide as the 

 length of their vertebral centra, and each is channeled on its anterior 

 edge to receive the edge of the next preceding neural process. Pos- 

 teriorly they become more slender and wider apart. They nearly coin- 

 cide in number with the spine-bearing interneurals, but they are only 

 half as numerous as the ray-bearing ones, as are also the haemal pro- 

 cesses as compared with the interhaemal rays. 



The first developed parapophyses occur on the fourth vertebra, 

 though a rudimentary pair is present on the third. They gradually 

 become longer posteriorly to the last pair, which are expanded into 

 a broad, trowel-shaped shield united to each other at the median line 

 and inclosing the end of the abdominal cavity. The parapophyses are 

 not connected by a transverse bridge across the base of each pair. 



Inferior and superior zygopophyses are well developed. The inter- 

 spinous bones of two vertebrae anterior to the hypural assist in support- 

 ing the caudal. 



The first two vertebrae have epipleurals only. Anteriorly the epi- 

 pleurals are attached to the bases of the ribs, but posteriorly they creep 

 up to the vertebral centra. They are present behind the abdominal 

 cavity for a considerable distance. 



