dorsal surface of the element has a groove in the midline 

 which superficially separates the element into right and 

 left halves, but the ventral surface shows no such groove. 

 Posteriorly the element becomes divided into four 

 slender rods, the tips of which project posteriorly a short 

 distance beyond the end of the encasing scales, through a 

 hole in the posterodorsal surface of the last scale seg- 

 ment. A large plug of cartilage intermediates between 

 the bifurcate anterior end of the fin-ray element and the 

 posterior end of the pelvis. The fin-ray element is 

 movable in a dorsoventral plane around the posterior end 

 of the pelvis, for ligaments are attached to the dorsal and 

 ventral halves of the anterior end of the element, and the 

 ligaments connect anteriorly to strong muscles. The ven- 

 tral ligament runs along a concavity on the ventral sur- 

 face of the pelvis to its muscle, while the dorsal ligament 

 runs anteriorly through a longitudinal tunnel in the basal 

 region of the dorsal lobe of the pelvis to make contact 

 with its muscle, which is housed in a concavity along the 

 dorsal surface of the pelvis anterior to the dorsal lobe. 

 The pelvis itself is movable in a dorsoventral plane 

 around its fibrous tissue attachment between the ventro- 

 medial edges of the cleithra. 



VERTEBRAL COLUMN. —All vertebrae with bicon- 

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

 plate representing the fused centrum, hypurals, and 

 parhypural. 



Abdominal Vertebrae. 



First vertebra. — Neural spine enlarged, somewhat 

 laterally expanded, bifid to the centrum and thus not 

 forming a bony roof over the neural canal; articulates by 

 fibrous tissue and slight interdigitation along all of the 

 anterior face of its neural spine with the exoccipitals. The 

 rim of the concave anterior face of its centrum ar- 

 ticulates by fibrous tissue with the rim of the concave 

 posterior end of the basioccipital, while the rim of its pos- 

 terior face articulates similarly with the rim of the an- 

 terior face of the second vertebra. From about the mid- 

 dle of its posterolateral surface, the centrum possesses a 

 posteroventrally directed process which makes fibrous 

 tissue contact over the anterior half of the lower surface 

 of the centrum of the second vertebra. The neural pre- 

 zygapophysis of the second vertebra makes close fibrous 

 tissue contact with the dorsolateral surface of the first 

 vertebral centrum. 



Other abdominal vertebrae. — In five specimens the 

 abdominal vertebrae numbered seven. Except for the 

 first vertebra, all the abdominal vertebrae, as well as all 

 of the caudal vertebrae except the last, possess bony 

 roofs over the neural canal and have single, undivided 

 neural spines. The neural spine of the third vertebra is 

 the largest of those of the abdominal vertebrae, for it is 

 much expanded dorsally. The basal regions of the neural 

 spines and the dorsal regions of the neural arches become 

 increasingly anteroposteriorly enlarged, from the second 

 to the last abdominal vertebra, into broad articular sur- 



faces. These enlarged neural spines may have their an- 

 terior and posterior edges interdigitated with the 

 preceding and succeeding neural spines in large 

 specimens, but normally they articulate with one 

 another only by fibrous tissue. Each neural arch has a 

 neural foramen in its lateral surface. Short haemal post- 

 zygapophyses are present which slightly overlie the ven- 

 trolateral surface of the succeeding vertebral centra, but 

 there are no haemal prezygapophyses. The second to the 

 seventh abdominal vertebrae possess processes from 

 their centra which bear all but one of the seven 

 epipleural ribs. These processes become increasingly 

 longer and stouter posteriorly in the series. The second 

 vertebra bears a short lateral projection from its cen- 

 trum just below the anterior region of the neural arch, 

 and this projection articulates by fibrous tissue with the 

 first epipleural. The third to fifth vertebrae bear their 

 transverse processes progressively lower on their centra, 

 so that the fifth vertebra has its transverse process taking 

 its origin from the anteroventral edge of the centrum, 

 while the process itself is directed posteroventrally. The 

 third to the fifth vertebrae bear, respectively, the second 

 to fourth epipleurals from the dorsal surfaces of their 

 transverse processes. The processes of the sixth and 

 seventh vertebrae differ from those anterior to them in 

 that from the medial surface of the process on each side 

 of the centrum there is a medially directed projection 

 which meets and is continuous with that of its opposite 

 member, completely enclosing the haemal canal. The 

 haemal arch of the sixth vertebra does not have a haemal 

 spine, but that of the seventh vertebra does. The haemal 

 spine of the seventh vertebra, however, is not a single 

 medial piece. Rather, it is bifid and forms a short 

 posteroventrally directed process on either side of the 

 midline. The sixth and seventh vertebrae bear, respec- 

 tively, the fifth and sixth epipleurals from the lateral sur- 

 faces of their haemal arches. The neural spine of the fifth 

 vertebra articulates by fibrous tissue dorsally with the 

 supraneural strut that supports the posterior end of the 

 spiny dorsal fin pterygial elements, while posterodor- 

 sally it articulates with the first basal pterygial element 

 of the soft dorsal fin. The neural spines of the sixth and 

 seventh vertebrae articulate by fibrous tissue between, 

 respectively, the first and second and the second and 

 third basal pterygial elements of the soft dorsal fin. 



Caudal Vertebrae. — The caudal vertebrae numbered 

 11 in five specimens. As with the more posterior of the 

 abdominal vertebrae, the first two caudal vertebrae have 

 their neural spines enlarged. From the third to the last 

 vertebra, however, the degree of enlargement progres- 

 sively decreases so that the more posterior caudal verte- 

 brae have relatively normal neural spines. All of the 

 caudal vertebrae, except the last, possess complete 

 neural and haemal arches. There are no haemal pre- 

 zygapophyses, and small haemal postzygapophyses are 

 only developed on a few of those vertebrae supporting the 

 anal fin. The first caudal vertebra has a thick haemal 

 spine that articulates firmly by fibrous tissue with the 

 upper anterior surface of the enlarged first anal fin basal 



