abruptly changing on the middle of the side of the body 

 to plain pale below. It also has the olfactory epithelium 

 less folded than in the other species, the folds confined to 

 the rear wall of the sac and the enlarged folds not them- 

 selves bearing elaborate folds, and fewer dorsal and anal 

 fin rays. In scleratus the dorsal rays are usually 10 to 12 

 and in the other species 13 to 15, while the anal fin usual- 

 ly has one less ray than the dorsal in all of the species. 

 While the depressed body and caudal peduncle are 

 specializations in some way associated with its probably 

 rapid swimming, and its color pattern unique in the 

 genus, the less elaborate folding of the olfactory 

 epithelium is probably a more generalized condition than 

 in the other species. Since the majority of tetraodontids 

 have relatively short-based fins with relatively few rays, 

 as does Triodon, I would think that the moderate number 

 of rays in scleratus is more generalized than the larger 

 number in the other species. 



There are more numerous internal differences between 

 the species of Lagocephalus. A specialized dorsal flange 

 of the parasphenoid in the interorbital septum that 

 meets and sutures with the ventral surface of the frontals 

 is present in laevigatas, lagocephalus, lunaris, and 

 spadiceus but is absent in inermis and scleratus. In 

 laevigatus and lagocephalus the pteroaphenoid is in con- 



Figure 258.— Dorsal views of skulls of: 



A, Sphoeroidet dortalit, 155 mm SL, Florida; 



B,S. nepheliu, 128 mm SL, Bahamas: 



C, 5. lobattu, 67.5 mm SL, Panama (Pacific). 



tact with the dorsal flange of the parasphenoid, but not 

 in the other two species with a dorsal flange. A single 

 hypohyal is present in all species except laevigatus, 

 which retains the more generalized condition of both a 

 dorsal and ventral hypohyal. The first pharyngo- 

 branchial is toothless in laevigatus, lagocephalus, and 

 spadiceus, but in lunaris it bears a few minute teeth 

 (much smaller than those on the second and third 

 pharyngobranchials) and in inermis and scleratus 

 numerous minute teeth, the retention of numerous teeth 

 being the most generalized condition. 



A feature of the skull unique to Lagocephalus among 

 the tetraodontids is the development of a posterolateral 

 wing of the frontal which meets or closely approaches the 

 posterodorsal surface of the pterotic to completely or par- 

 tially roof over a temporal fossa. These specialized wings 

 are best developed in lunaris, laevigatus, spadiceus, and 

 lagocephalus (in respective increasing order of greatest 

 size and length of the wing), in which their wings usually 

 make direct contact with the pterotic to completely roof 



