rays that can be assigned to the anal portion of the pseu- 

 docaudal fin. The lowermost, or first, modified anal fin 

 basal pterygiophore is placed at about a right angle to 

 the vertebral column, but the second to eighth modified 

 basal pterygiophores are progressively more obliquely 

 placed so that the eighth is placed about parallel to the 

 vertebral column. The first modified basal pterygio- 

 phore articulates distally with the inner edge of the car- 

 tilaginous plate that forms the medial pterygiophore of 

 the anal fin, while proximally it articulates by fibrous tis- 

 sue with the posterior edge of the last unmodified anal fin 

 basal pterygiophore. The second modified basal pteryg- 

 iophore ends distally at its medial pterygiophore, which 

 is continuous with the medial pterygiophore of the anal 

 fin and is delimited from it only by a slightly constricted 

 region of cartilage. The anterior edge of the second mod- 

 ified basal pterygiophore articulates proximally by 

 fibrous tissue with the posterior edge of the first modi- 

 fied basal pterygiophore. The third to fifth modified 

 basal pterygiophores articulate proximally by fibrous tis- 

 sue with the posterior edge of the haemal spine of the 

 seventh caudal vertebra, while the sixth to ninth modi- 

 fied basal pterygiophores articulate with the posterior 

 edge of the haemal spine of the eighth caudal vertebra. 

 Distally the modified basal pterygiophores connect with 

 the calcified cartilage of their medial pterygiophores. 

 The medial pterygiophores distal to the third to the sev- 

 enth modified basal pterygiophores are separate from 

 one another, but that distal to the eighth modified basal 

 pterygiophore is continuous with the calcified cartilage 

 at the end of the ninth caudal vertebra and with the 

 medial pterygiophore distal to the seventh modified 

 basal pterygiophore of the dorsal portion of the pseudo- 

 caudal fin. The distal pterygiophores of calcified carti- 

 lage in the anal portion of the pseudocaudal fin have the 

 same structure as those of the dorsal portion. The lower- 

 most fin ray of the anal portion of the pseudocaudal fin is 

 branched in a double dichotomy, but the other seven fin 

 rays of the anal portion are simply divided distally into 

 two terminal segments. None of the rays are cross- 

 striated, and bony ossicles have just begun to form, just 

 as in the dorsal portion, in the two study specimens. 



The pseudocaudal fin, as here defined, thus consists of 

 15 fin rays, the uppermost ray and lowermost ray of 

 which are branched in double dichotomies, while the 

 other 13 rays are simply bifurcate distally. The upper 

 seven rays belong to the dorsal fin and are supported by 

 seven bony modified dorsal fin basal pterygiophores, as 

 well as by calcified cartilages which form a medial and a 

 distal series. The lower eight rays belong to the anal fin 

 and are supported by eight bony modified anal fin basal 

 pterygiophores, as well as by calcified cartilages which 

 form a medial and a distal series. The dorsal and anal fin 

 rays form a continuous series around the posterior end of 

 the body, with those dorsal to the ninth caudal vertebra 

 being considered as dorsal fin rays and those ventral to 

 that vertebra being considered as anal fin rays. The divi- 

 sion of the dorsal and anal fin rays into those of the dor- 

 sal and anal fins proper and those of the pseudocaudal 

 fin is arbitrary, but convenient. 



Anatomical diversity. —While three genera of molids 

 are presently recognized, there is some doubt regarding 

 the number of species in two of them, as most recently 

 revised (Fraser-Brunner 1951). Ranzania is monotypic 

 {laevis = truncatus). Masturus is probably monotypic, 

 Fraser-Brunner stating that the two forms he tenta- 

 tively recognized as specifically distinct were probably 

 only the sexes of a single species (lanceolatus =oxyu- 

 ropterus). Fraser-Brunner believed that Mola was repre- 

 sented by two species, the worldwide M. mola being 

 largely replaced in the south Pacific by M. ramsayi, the 

 latter differing from M. mola mainly in having several 

 more fin rays in the pseudocaudal fin, larger bony ossi- 

 cles at the distal ends of these rays, and no band of 

 smaller scales along the base of the pseudocaudal fin. 



Subsequent to Fraser-Brunner's (1951) revision, a new 

 genus and species of molid has been described, 

 Pseudomola lassarati Cadenat (1959), based on a single 

 specimen from west Africa. The specimen was thought to 

 be unusual by the presence of a large white abdominal 

 region and additional white spots and reticulations. It 

 otherwise was said to differ from Mola only in lacking, at 

 its large size (1,090 mm total length), bony ossicles at the 

 distal ends of at least some of the rays of the pseudo- 

 caudal fin and to differ from Masturus only by lacking 

 the posteriorly prolonged lobe of the pseudocaudal fin. 

 This lobe is often lost (bitten off?) in Masturus and even- 

 ly healed over, while little is known about variation in 

 the time of development of the ossicles in Mola. 

 Pseudomola lassarati could easily be a Mola mola that 

 has not yet developed the bony ossicles along the edge of 

 the pseudocaudal fin or a Masturus lanceolatus that has 

 lost the posterior lobe of the pseudocaudal fin. However, 

 some specimens of M. lanceolatus are known to have a 

 white abdominal region and additional white spots or 

 blotches (see photographs in Gudger 1937a, b) very simi- 

 lar to those of P. lassarati, and it is probably with M. 

 lanceolatus that P. lassarati is synonymous. 



A fossil species of molid, Mola pileatus (Beneden), is 

 known from the Miocene on the basis of the bony ossicles 

 that are present in the skin above and below the mouth, 

 just as in the Recent species of Mola (these being the 

 remains of the postlarval skin spines, according to 

 Fraser-Brunner 1951:110) and of a few fused premaxil- 

 laries and dentaries that are more molidlike than diodon- 

 tidlike (see Leriche 1907 and 1926, and contained refer- 

 ences, and Deinse 1953). 



Fraser-Brunner (1951) distinguished Ranzania (as the 

 Ranzaniinae) from Mola and Masturus (Molinae) as 

 follows: Ranzania more elongate; vertebrae 8 -I- 10 or 11 

 (vs. 9 -(• 8); carapace of hexagonal plates (vs. a colla- 

 genous carapace); lips produced and funnellike (vs. lips 

 normal); gill rakers free (vs. concealed in thick skin); 5 

 branchiostegal rays (vs. 6); no secondary postlarval meta- 

 morphosis (vs. the development of prominent spiny proc- 

 esses from the body during a Molacanthus stage). Mas- 

 turus was distinguished from Mola by having the middle 

 fin rays of the pseudocaudal fin not supported basally 

 by basal pterygiophores and none of the pseudocaudal 

 fin rays developing bony ossicles at their distal ends. 



377 



