PROCEEDINGS OF THE NATIONAL MUSEUM. 



Inferior zygapopliyses developed as large spines, each anterior spiue 

 tlie longer and pointing obliquely forward; each posterior pointing 

 obliquely backward at right angles, meeting it at its middle. 



Hypnral assisted in supporting caudal fin by spines of two iDreceding 

 vertebra} and two auxiliary spines substituting neural spine of first 

 preceding vertebra. 



First rib very small, placed" on second vertebra. Second, two or 

 three times as long and abruptly widened at its upper end. Others 

 normal. 



Four epipleurals only present. First placed on first vertebra, unac- 

 companied by a rib. Other three on first three ribs. 



OSTEOLOGY OF SPHYEJENA ARGENTEA. 



Orauium elongate and narrow, forming a narrow isosceles triangle, as 

 viewed from above. 



Supraoccipital scarcely interposed between exoccipitals. Its crest 

 extending far back as a thin plate of bone, dividing into numerous 

 bristle-like filaments. 



Exoccipitals meeting above basioccipital, completely surrounding 

 foramen magnum. 



ExocciiDitals and basioccipital produced backward, elongating fora- 

 men magnum, which runs tunnel-like into brain cavity. 



Parietals widely separated by supraoccipital, their posterior ends 

 overlapping epiotics. 



Epiotics extending backward in bristle-like filaments similar to 

 supraoccipital. 



Upper limb of posttemporal firmly attaclied to upper part of epiotic 

 process rather than to main part of bone. 



Opisthotics sending a spinelike process backward, to base of which 

 lower limb of post-temporal rather loosely attaches itself by ligament. 



Prootics produced anteriorly in a spinelike process. 



Sphenotics large, separated from frontal at middle portion by a large 

 foramen. 



Alisphenoids meeting at their upper edges. They restrict the anterior 

 opening into brain case to a comparatively small foramen. 



Basisphenoid present, a foramen between it and basis cranii, its 

 descending process reaching to and broadly attaching to parasphenoid. 



Myodome present, not opening to exterior at posterior end. 



Frontals elongate, covering two-thirds of length of skull. 



Prefrontals very elongate, the olfactory foramen within their poste- 

 rior fourth. 



Ethmoid entirely superior in position, overlying anterior i^artof pre- 

 frontals and posterior part of vomer, forming edge of rostrum between 

 prefrontals and vomer. 



Nasals long, channeled rods of bone fully one third length of cranium 

 firmly attached in a groove between frontals and prefrontals and con- 

 tinued along upi^er part of ethmoid and vomer. 



