supraoccipital epiotic 



pterosphenoid frontal 

 basisphenoid 



exoccipital 



cartilage 

 prefrontal 

 ethmoid 

 palatine 

 ectopterygoid 



interopercuiuin 



operculum 

 suboperculum 



, . , V preoperculum ^ 



symplectic \ \ "^ "^ 



quadrate metapterygold parasphenoid / 



mesopterygoid 



I would slightly modify some of the above statements. 

 The body depth in Ramania is about 3 times in the stan- 

 dard length in the young, but large adults are deeper 

 bodied, the depth being only twice, or slightly less than 

 twice, in the standard length. In Mola and Masturus the 

 depth is usually between one and one and a half in the 

 standard length, with the young slightly less deep bodied 

 than large adults. The individual scale plates in Ran- 

 zania are thicker and more angular (often being hexa- 

 gonal) than in Mola and Masturus, whose scale plates are 

 more or less circular. However, the carapace of Ranzania 

 is relatively thin, for in Mola and Masturus the thinner 

 scale plates rest upon a thick layer of collagenous connec- 

 tive tissue. The funnellike mouth in Ramania, which 

 when closed forms a vertical slit, is unique among the 

 plectognaths. The gill rakers in the specimens of Mola 

 and Masturus examined here, none of which are large 

 adults, do not have the gill rakers concealed in thick 

 skin, although a flap of skin from the leading edge of the 

 raker to the gill arch strengthens their articulation to the 

 arch, more so than in Ramania. It is apparently only in 

 large adults of Mola and Masturus that the gill rakers 

 become more concealed. In the four specimens of Ran- 

 zania either cleared and stained or radiographed, the 

 vertebrae were 8 -(- 10 = 18, while in two specimens of 

 Mola they were 8 + 9 = 17 and in two oi Masturus 8-1-8 

 = 16, and it would appear that eight is the normal 



Figure 307.— MoJa mola: lateral view of 

 head, composite based on two specimens, 

 306 and 310 mm SL, California. 



number of abdominal vertebrae in molids and that there 

 is a modal difference of one caudal vertebra between the 

 three genera. It is possible that Fraser-Brunner's counts 

 of nine abdominal vertebrae in Mola and Masturus were 

 made from radiographs and that the anterodorsal prongs 

 of the basioccipital were mistaken for the first vertebra. 

 A few additional external characters distinguish Ran- 

 zania from Mola and Masturus. In Ramania the pectoral 

 fin is relatively longer and more falcate, and fits into a 

 shallow concavity on the carapace when folded back, 

 while in Mola and Masturus the pectoral fin is shorter 

 and more rounded, and there is no concavity for it on the 

 carapace. In Ramania the rays of the pseudocaudal fin 

 are highly branched distally, while in Mola and 

 Masturus they are usually not branched in more than 

 single to triple dichotomies. In young Ranzania the distal 

 edge of the pseudocaudal fin is relatively rounded and 

 not set off distinctly from the dorsal and anal fins, much 

 as in both young and adult Mola and Masturus. In adult 

 Ranzania, however, the distal edge of the pseudocaudal 

 fin becomes relatively straight and slightly oblique, and 

 is distinctly set off from the dorsal and anal fins. 



379 



