panded more or less flat plate of decreasing width an- 

 teriorly and its lower surface a similarly flat vertical 

 plate of decreasing depth anteriorly; supraoccipital with 

 a high well-developed crest throughout most of its 

 length, the dorsal edge of the posterior end of the crest of- 

 ten indicated externally by a break in the contour of the 

 dorsal profile; posterolateral region of frontal prolonged 

 laterally as two flanges whose distal ends closely ap- 

 proach or are in contact with one another to form a par- 

 tial to complete bony well around the muscle mass 

 leading to the operculum; sphenotic mostly excluded 

 from the dorsal surface of the skull, mostly confined to 

 the ventrolateral surface of the skull behind the orbit; 

 base of prefrontal well removed from the vomer, broadly 

 separated from it by the ethmoid and parasphenoid; 

 trituration teeth never present; a single nostril on each 

 side, set in a very low inconspicuous tube; lateral line in- 

 conspicuous, apparent only with magnification; gill 

 opening restricted, extending ventrally no further than 

 about the level of the middle of the pectoral fin base; 

 vertebrae always modally 17; vertebral column highly 

 arched anteriorly, the axis of the arched portion highly 

 oblique to that of the skull; haemal arches and spines es- 

 pecially well developed on most of the abdominal verte- 

 brae. 



Detailed description of Lagocephalus laevigatus. 



Material examined— Three cleared and stained 

 specimens, 61.4-166 mm; one wet completely disar- 



ticulated specimen, approximately 290 mm, prepared by 



maceration; one dry skeleton, approximately 290 mm. 



Occipital Region. 



Basioccipital. —A short column, slightly expanded 

 anteriorly; cartilage filled at its anterior and antero- 

 lateral edges; articulates by interdigitation anteriorly 

 with the slightly overlying parasphenoid, anterolaterally 

 with the prootic and laterally with the exoccipitals. The 

 anterodorsal end of the basioccipital reaches to and 

 forms the lower posterior wall of the vestigial myodome 

 (see description of the prootic). The rim of the round con- 

 cave posterior end of the basioccipital articulates by fi- 

 brous tissue with the rim of the concave anterior face of 

 the centrum of the first vertebra. The posterodorsal sur- 

 face of the basioccipital forms the ventral wall of the 

 foramen magnum. 



Exoccipital. — Cartilage filled at its anterior and 

 ventromedial edges; articulates by interdigitation ven- 

 tromedially with the basioccipital, posterolaterally with 

 the pterotic, anterodorsally with the epiotic, and antero- 

 ventrally with the prootic. Dorsomedially the exoc- 

 cipital forms the lateral wall of the foramen magnum, 

 while the dorsal wall of the foramen is formed by the 

 close fibrous tissue articulation of the extreme dorso- 

 medial edges of the two exoccipitals. Ventrally the 

 foramen magnum is closed not by medial projections of 



Figure 194.— Lagocephalus laevigatus (above), 



with L. lunaris (center) and 



L. scleratus (below) for comparison: in all 



three examples, upper left, nasal region as 



seen externally (far left) and the olfactory 



lamellae as seen with the top of the nasal 



sac removed (center), and the outline of an 



anteroposterior cross section of the sac and 



lamellae; center left, scales from upper 



middle region of body, including, in L. 



lunaris and L. scleratus, the small scales 



associated with the lateral line. 



