36 U.S. NATIONAL MUSEUM BULLETIN 2 84 



length. The anterior end of the fii'st centrum articulates with the basi- 

 occipital. There is a neural spine present on all but the first two and 

 last centra. The neural arches of the first two vertebrae are complete 

 (fused above). The neurapophyses (neural prezygapophyses) of the 

 first vertebra are enlarged, directed dorsally, and articulate with the 

 exoccipital condyles. The first recognizable neural postzygapophyses 

 are on the fidtth vertebra. The centra of the first three vertebrae bear 

 posteriorly directed processes ventrally that overlap the next suc- 

 ceeding centrum. These processes are not serially homologous with 

 the neural or haemal pre- or postzygapophyses. The third through 

 sixth vertebrae bear concave parapophyses that articulate with the 

 heads of the first through fourth pleural ribs on each side. The para- 

 pophyses are unmodified on the seventh and eighth vertebrae and 

 articulate on their mesial surface with the fifth and sLxth pleural ribs 

 on each side. The ninth and tenth vertebrae bear parapophysial stays 

 (Makushok, 1958) connecting the parapophyses, which articulate 

 respectively with the seventh and eighth ribs on each side. The 

 eleventh vertebra (first caudal vertebra) bears the first haemal spine 

 and the ninth (terminal) pair of pleural ribs, which articulate with 

 the haemal arch. All the caudal vertebrae except the hypural bear 

 distinct haemal spines. The first epipleurals are attached to the neural 

 arch of the first vertebra. The succeeding epipleurals are attached 

 gradually more ventrally on the succeeding vertebrae. The second 

 pair of epipleurals are attached to the neural arch of the second 

 vertebra; the third through eighth are attached to their respective 

 pleural ribs on the thu'd through eighth vertebrae, and the ninth 

 through thirteenth (terminal) are attached to the lateral surface of 

 the nonautogenous parapophyses of their respective haemal arches on 

 the ninth through thirteenth vertebrae. The first recognizable haemal 

 prezygapophysis appears on the tweKth vertebra; and the first 

 noticeable haemal postzygapophysis, on the ninth vertebra. 



The neural and haemal spines of the antepenultimate and penul- 

 timate vertebrae are nonautogenous. The haemal spine of the penul- 

 timate vertebra is modified for participation in support of the ventral 

 procurrent rays of the caudal fin; the neural spine is reduced (absent?) 

 and does not participate in support of the fin. There are eight un- 

 segmented, unpaired, dorsal procurrent caudal rays, and seven un- 

 segmented, unpaired, ventral procurrent caudal rays. (Of six other 

 specimens examined, all had eight dorsal procurrent caudal rays; five 

 had seven and one had eight ventral procurrent caudal rays.) There 

 are 13 segmented rays in the caudal fin, the middle nine of which are 

 branched (once). There are two epurals that attach anteriorly in a 

 median groove on the dorsal surface of the urostylar portion of the 



