12 



BULLETIN 189, UNITED STATES NATIONAL MUSEUM 



Pterygoids. — A pair of bones in the roof of the mouth, behind the palatines, some- 

 times bearing teeth. 



Pyloric caeca. — Blind appendages connected with the pyloric or lower end of the 

 stomach. 



Ray. — A bony or cartilaginous support of a fin; rays are spiny or soft. 



Scute. — An external bony or horny plate. 



Spiracles. — A pair of openings in the dorsal surface of the head in some sharks and 

 skates. 



Standard length. — Distance from tip of snout or tip of lower jaw, whichever is the 

 longer, to base of caudal, or end of last vertebra (see fig. 3). 



Suborbital. — The bone just below the eye. 



• TOTAL LENGTH 



pqeopercle: 

 maxillarv 

 pre max i ll arv 

 'mandible 



LATEPIAL LINE 

 ■PECTORAL FIN 

 -VENTRAL FIN 



OPERCLE TURNED BACK 

 PSEUOOBRANCHIAE 



UPPER LIMB OF eiLL ARCH WITH RAKEFiS 

 LOWER LIMB 

 eiLL FILAMENTS 



Figure 3. — Diagram of the corbina {Sciaena gilberti Abbott), showing external parts and 

 the name of each used in the descriptions and keys. 



Suborbital stay. — A bone extending across the cheek, to or toward the preopercle; 

 present in a few groups only. 



Supplemental maxillary. — A small bone placed on the upper margin of the maxil- 

 lary, if present. 



Symphysis. — The tip of the chin; the point of juncture of the two bones of lower 

 jaw. 



Synonymy. — A list of technical names applied to a genus or species. 



Tenaculum. — An adhesive structure, as in the claspers of male sharks and chi- 

 maeras. 



Thoracic. — Pertaining to the thorax; said of the ventral fins, if attached more or 

 less below the pectoral fins. 



Trenchant. — Compressed to a sharp edge. 



Tritors. — Teeth with grinding surfaces. 



