bra do not fuse with one another above the neural canal, 

 but, rather, have their medial surfaces closely apposed 

 and articulated with one another by fibrous tissue. This 

 dorsomedial region of apposition is thickened and pro- 

 longed anteriorly and posteriorly into a neural spine 

 whose right and left halves are likewise closely apposed 

 medially and held together by fibrous tissue. The ven- 

 tral surface of the anterior prolongation of the neural 

 spine of the second vertebra overlies the dorsal edge of 

 the bifid neural spine of the first vertebra and effectively 

 roofs over the neural canal in this area. The posterior pro- 

 longation of the neural spine of the second vertebra over- 

 lies the anterior edge of the neural arch and base of the 

 neural spine of the third vertebra. The neural arches and 

 spines of the third and fourth abdominal vertebrae are 

 likewise only closely apposed, with fibrous tissue hold- 

 ing the right and left halves closely together. The neural 

 spines of the third and fourth abdominal vertebrae are 

 prolonged only posteriorly, and overlie the neural arch 

 and spine of the vertebra just posterior to them. The pos- 

 terodorsal end of the neural spine of the fourth abdom- 

 inal vertebra articulates by fibrous tissue with the ven- 

 tral edge of the first dorsal fin basal pterygiophore. The 

 right and left sides of the neural arches of the fifth to 

 eighth abdominal vertebrae fuse to one another in the 

 midline above the neural canal and are prolonged pos- 

 terodorsally into long, stout, undivided neural spines. 

 The lower posterior edges of these neural spines overlie 

 the anterior edges of the neural arches of the vertebra 

 just posterior to them. More distally the neural spines of 

 the fifth to eighth abdominal vertebrae articulate by 

 fibrous tissue between the more anterior of the dorsal fin 

 basal pterygiophores. 



Caudal Vertebrae. — Nine caudal vertebrae in two 

 specimens. With the exception of the last two vertebrae, 

 all of the caudal vertebrae have well-developed and un- 

 divided neural and haemal spines. The neural and hae- 

 mal spines decrease slightly in stoutness, but not partic- 

 ularly in length, posteriorly in the series. The degree of 

 anteroposterior expansion of the neural arch and base of 

 the neural spine decreases from the first to the sixth cau- 

 dal vertebrae so that the neural spines of the sixth and 

 seventh caudal vertebrae are slender shafts throughout 

 their entire lengths. The neural spines of the first to sev- 

 enth caudal vertebrae support by fibrous tissue the more 

 posterior of the dorsal fin basal pterygiophores. The dis- 

 tal three-fourths of the haemal spines of the first and sec- 

 ond caudal vertebrae articulate with one another by fi- 

 brous tissue and the thick shaft thus formed is overlain 

 laterally and anteriorly by the deeply concave posterior 

 surface of the enlarged first anal fin basal pterygiophore. 

 The posterior edge of the haemal spine of the second cau- 

 dal vertebra articulates with the anterior edge of the sec- 

 ond anal fin basal pterygiophore. The haemal spines of 

 the third to seventh caudal vertebrae support the other 

 anal fin basal pterygiophores. The size of the neural and 

 haemal canals through the neural and haemal arches of 

 the caudal vertebrae decreases posteriorly in the series 

 until these canals are very narrow in the seventh caudal 



vertebra. The short neural spine of the eighth caudal ver- 

 tebra arises directly from the centrum and contains no 

 canal whatsoever. The haemal process, however, of the 

 eighth caudal vertebra contains an extremely narrow 

 canal through its substance in one of the specimens but 

 not in the other. The neural and haemal spines of the 

 eighth caudal vertebra curve anteriorly and their distal 

 ends articulate with, respectively, the posterior edges of 

 the neural spine and of the haemal spine of the seventh 

 caudal vertebra. The ninth caudal vertebra is a simple 

 shaft which ends posteriorly with a flat surface abutting 

 against a calcified cartilage, explained below. 



DORSAL. ANAL, AND PSEUDOCAUDAL FINS. — 



While a larval caudal fin fold without rays is present in at 

 least the molids Masturus and Ranzania, this is lost in 

 development and the adult pseudocaudal fin in molids is 

 apparently a secondary formation from dorsal and anal 

 fin rays (Gudger 1937a, b; Raven 1939a; Tyler 1970b). 

 The fin rays of the pseudocaudal fin are continuous with 

 those of the dorsal and anal fin series and are supported 

 basally by modified basal pterygiophores of the dorsal 

 and anal fins. Only an arbitrary distinction can be made 

 between the dorsal, pseudocaudal, and anal fins, but 

 such a distinction is perhaps advisable for the sake of dis- 

 cussion. The pseudocaudal fin, composed of postero- 

 medially migrated dorsal and anal fin rays, is here con- 

 sidered to include all those fin rays supported by the 

 modified basal pterygiophores posterior to the neural and 

 haemal spines of the seventh caudal vertebra. 



The 15 dorsal fin basal pterygiophores and the 9 anal 

 fin basal pterygiophores anterior to the seventh caudal 

 vertebra have a normal relationship with the neural and 

 haemal spines of the vertebrae to which they articulate. 

 The ventral ends of these dorsal fin basal pterygiophores 

 are cartilage filled while the distal ends of all but the first 

 dorsal fin basal pterygiophore are irregularly cartilage 

 filled and closely apposed to the ventral surface of the 

 large cartilaginous plate that intervenes between them 

 and the dorsal fin rays. The first dorsal fin basal pteryg- 

 iophore tapers to a point distally and articulates by fi- 

 brous tissue posteriorly with the neural spine of the fifth 

 abdominal vertebra and with the anterior edge of the sec- 

 ond basal pterygiophore. Along the dorsal third of its 

 anterior edge the first basal pterygiophore articulates by 

 fibrous tissue, and possibly slight interdigitation, with 

 the posteroventral edge of the supraneural. The supra- 

 neural tapers to a blunt point anteriorly and is embedded 

 between the right and left muscle masses of the dorsal 

 fin. The large cartilaginous plate that intervenes between 

 the basal pterygiophores and the dorsal fin rays is calci- 

 fied irregularly in the two cleared and stained specimens. 

 The posterior one-third of the plate is the best calcified 

 portion, but calcareous areas are also present at the ante- 

 rior end and along much of the ventral portion of the 

 plate. The plate is homogenous posteriorly, but shows 

 some evidence anteriorly of being composed of succes- 

 sive cartilaginous blocks closely applied to one another. 

 The lateral surface of the plate possesses upraised areas 

 between which run the ligaments from the fin rays to the 



