with the third being slightly larger than the second. The 

 fourth actinost is only concave on the side toward the 

 third actinost. The actinosts articulate with one another 

 dorsally through cartilage and ventrally, except for the 

 small first actinost, with one another by slight interdigi- 

 tation. The second actinost interdigitates antero- 

 ventrally with the base of the scapula, while the second 

 to fourth actinosts articulate ventrally through cartilage 

 with the coracoid. Distally the actinosts support all of 

 the fin rays, except for the small first fin ray, which ar- 

 ticulates with the scapula. 



Fin rays. — Usually 17 to 19 fin rays present; the 

 first ray small, its medial half thicker than its lateral 

 half; first ray articulated with the scapula, but the other 

 rays articulated to the actinosts. The first two rays and 

 last ray unbranched, the other rays branched. First ray 

 without cross-striations, the other rays cross-striated. 



VERTEBRAL COLUMN. —All vertebrae with bicon- 

 cave centra, except the last, which ends posteriorly in the 

 modified urostyle and fusion with some of the hypurals. 



Abdominal Vertebrae. 



First vertebra. — Neural spine befid and relatively 

 short; neural arch with a complete bony roof over the 

 neural canal, as do all the other vertebrae; articulates by 

 fibrous tissue laterally at a shallow but broad concavity 

 over the upper anterior half of its centrum with the 

 posteroventrally projecting spinelike exoccipital con- 

 dyles. Along the lizn of its concave anterior end the 

 centrum articulates by fibrous tissue with the rim of the 

 round posterior end of the basioccipital. The first 

 vertebra articulates by fibrous tissue poaterodorsally at a 

 shallow concavity on its lateral surface with the neural 

 prezygapophysis of the second vertebra, while 

 posteroventrally from its lateral edge it sends a large 

 process posteriorly to fit under a shallow groove on the 

 anterior half of the ventrolateral surface of the centrum 

 of the second vertebra. 



Other abdominal vertebrae. — In 12 specimens, the 

 abdominal vertebrae numbered eight. The second and 

 third abdominal vertebrae have bifid neural spines very 

 similar to that of the first vertebra. The fourth abdomi- 

 nal vertebra, however, has the neural spine bifid 

 anteriorly but single posteriorly. All the vertebrae, both 

 abdominal and caudal, posterior to the fourth abdominal 

 vertebra have undivided neural spines. The neural spines 

 of the fifth to eighth abdominal vertebrae become in- 

 creasingly thiimer and longer. From the second to eighth 

 abdominal vertebrae the neural and haemal prezy- 

 gapophyses gradually become larger, but the haemal 

 postzygapophyses remain about the same size so that 

 each of the last few abdominal vertebrae articulates ven- 

 trally by the apposition of its posteroventrally projecting 

 haemal postzygapophyses with the anteroventrally pro- 

 jecting haemal prezygapophyses of the vertebra pos- 



terior to it. No haemal arches or spines are present. The 

 neural spine of the seventh abdominal vertebra articu- 

 lates by fibrous tissue along its posterior edge with the 

 first basal pterygiophore of the dorsal fin, while the 

 neural spine of the eighth abdominal vertebra articu- 

 lates between the first and second basal pterygiophores 

 of the dorsal fin. 



Caudal Vertebrae. — In 12 specimens, the caudal 

 vertebrae numbered 11 in 10 specimens and 10 in 2 speci- 

 mens. All the caudal vertebrae, and only the caudal 

 vertebrae, possess haemal arches, while only those verte- 

 brae just below and posterior to the last basal pterygio- 

 phore of the anal fin possess large haemal spines. The 

 haemal arches of the first four caudal vertebrae (those 

 without conspicuous haemal spines) are modified for ar- 

 ticulation by fibrous tissue with the dorsal ends of the 

 basal pterygiophores of the anal fin. From the haemal 

 prezygapophyses of each of these vertebrae there is one 

 projection directed anteriorly and another directed pos- 

 teromedially. The anterior projections from the haemal 

 prezygapophyses on each side of the vertebra do not meet 

 in the midline under the centrum, while the postero- 

 medial projections from each side do meet and fuse in the 

 midline under the centrum at the open area between the 

 anterior projections from the haemal prezygapophyses of 

 the vertebra behind it. Thus, the posteromedial projec- 

 tions from the haemal prezygapophyses form the haemal 

 arch, which is here displaced posterodorsally from the 

 position it would more normally assume. The anterior 

 projections from the haemal prezygapophyses are much 

 shorter than the posteromedial projections, except in the 

 case of the first caudal vertebra, in which the anterior 

 projection is much enlarged and somewhat ventrally di- 

 rected for support along its ventral surface of the dorsal 

 end of the enlarged first basal pterygiophore of the anal 

 fin. The anterior projections from the haemal prezyga- 

 pophyses of the second and third caudal vertebrae sup- 

 port through fibrous tissue, respectively, the second and 

 third anal fin basal pterygiophores. The fourth caudal 

 vertebra supports the fourth and fifth anal fin basal 

 pterygiophores from, respectively, its anterior haemal 

 prezygapophyseal projections and from its haemal arch. 

 The fifth caudal vertebra supports the sixth anal fin 

 basal pterygiophore from its haemal arch. The fifth cau- 

 dal vertebra, in all but one of the study and radio- 

 graphed specimens, possesses a haemal spine. The pos- 

 teromedial projections of the haemal prezygapophyses of 

 the fifth caudal vertebra not only fuse to each other in 

 the midline, but also fuse to the ventrolateral edges of 

 the centrum, leaving open a medial canal beneath the 

 centrum and enclosing a large foramen laterally. From 

 the area of fusion with the centrum, a long haemal spine 

 is given off ventrally from the fifth caudal vertebra to 

 support by fibrous tissue the last anal fin basal pterygio- 

 phore. The haemal apparatus of the sixth to ninth verte- 

 brae is similar to that of the fifth vertebra in that the 

 haemal arch fuses posterolaterally to the centrum and 

 completely encloses the haemal canal, except laterally at 

 the foramen. The haemal spines of the sixth and seventh 



