Figure 32i.—Ranzania laevis: diagrammatic 

 representation of the relationships between 

 the basal pterygiophores of the dorsal, anal. 



and pseudocaudal fins and the neural and 

 haemal spines of the supporting vertebrae, 

 65.1 mm SL, Hawaii. 



Figure 325.— iJonzonia laevu: scales 



from upper middle region of body, to 



show the approximately hexagonal scale 



plates, articulated to one another by 



extensive minute interdigitations 



along all of their edges of contact 



(greatest length of largest scale 



plate 6.0 mm), 493 mm SL, Hawaii. 



jaw of Mola and Ranzania the trituration teeth are less 

 elongate than in the upper jaw and occur in a major 

 series to either side of the midline as well as in a series of 

 smaller teeth to either side lateral to the major series. In 

 Masturus the trituration teeth in the lower jaw are not 

 divided into right and left sets, but rather has a single 

 major series placed medially, lateral to which are two 

 series of smaller teeth on each side. 



In general configuration the pseudocaudal fin and its 

 supporting elements are much more similar in Mola and 

 Masturufi than in Ranzania. While a normally shaped 

 and placed larval caudal fin fold without rays is known to 

 be present in at least Masturus and Ranzania, this is lost 

 in development and the adult pseudocaudal fin in molids 

 is a secondary formation from posteromedially migrated 

 dorsal and anal fin rays and their basal pterygial sup- 

 ports, although it is possible that the rays in the central 

 nipple of the pseudocaudal fin of Masturus are remnants 



of true caudal fin rays (as believed by Fraser-Brunner 

 1951; see Tyler 1970b for discussion). 



In Ranzania the pseudocaudal fin is supported by the 

 last two caudal vertebrae. The last vertebra is a simple 

 rod seemingly representing a single centrum, which Leis 

 (1977) has shown to be a fusion product of two anlagen in 

 larval stages. The penultimate vertebra has relatively 

 well-developed neural and haemal spines which ante- 

 riorly support the last basal pterygiophores of the dor- 

 sal and anal fins and which posteriorly support the radial 

 elements of the pseudocaudal fin. Most of the radials 

 probably are posteromedially migrated basal pterygio- 

 phores (Tyler 1970b:27). There are seven radials above 

 and eight below in two of the three specimens of Ranza- 

 nia examined, but only six above and seven below in the 

 other (as also illustrated by Leis 1977:fig. 11), and a total 

 of 19 or 20 fin rays in the pseudocaudal lobe, while 

 Fraser-Brunner (1951) recorded 22 rays as the norm. 



