Jordan and Evennann. — Fishes of North America. 707 



Order Y. SYNENTOGNATHI. 

 (The wSynentognathous Fishes.) 



Lower pharyngeal bones fully united ; second and third superior pharyn- 

 geals variously enlarged, not articulated to the cranium, sending processes 

 forward; the fourth small or fused with the third. Vertebra; numerous 

 (45 to 70), the abdominal ones much more numerous than the caudal. 

 Ventral fins abdominal, without spine, the rays more than 5. Scapula 

 suspended to the cranium by a jiost-temporal bone, which is slender and 

 furcate. Articular bone of lower jaw with a small supplemental bone 

 perhaps corresponding to the coronoid bone. Parietal bones much 

 reduced, well separated by the supraoccipital. Supraclavicle not dis- 

 tinct; no interclavicles. No mesocoracoid. Maxillary very close to pre- 

 maxillary and sometimes firmly joined to it, the suture always distinct. 

 Basis of cranium double in front, but without muscular tube. No adipose 

 fin. Fins without spines. Lateral line concurrent with the belly, peculiar 

 in structure. Air bladder usually large, without pneumatic duct. Intes- 

 tinal tract simple, without pyloric cceca. This order* is allied to the Haplomi 

 on the one hand and to the Fercesoces on the other, and like these groups, it 

 marks the transition from the soft-rayed i o the spiuy-i ayed fishes. In their 

 anatomical characters the Sijncntognathi most resemble the latter, but 

 there are never spines in the fins, and the lower pharyngeals are united. 

 The group is divisible into four closely related families, Avhich have usually 

 been regarded as subfamilies of one family, Exocoetidw or Scomber esocidw. 

 The remarkable dift'erences in the pharyngeals seem to us to require the 

 division of the group into four families, the differential characters having 

 been first pointed out by Mr. Edwin C. Starks, a student in Stanford 

 University, {aw, together; ivro^, within; yvudoc, jaw.) {Physostomi, 

 part; family Scomheresocuhv , Giinther, Cat., vi, 233-298, 1866.) 

 a. Third superior pharyngeal ou each side scarcely enlarged, not longer than its anterior pro- 

 cess, and armed with comparatively few (about 15) pointed teeth; fourth superior 

 pharyngeal distinct on each side; lower pharyngeals united into a small linear plate, 

 armed with small teeth; vertebra; with zygapophyses; both jaws produced in along 

 beak iu the adult (the upper short in the young); teeth in jaws strong, unequal; max- 

 illaries firmly appressed to the premaxillaries; a distinct suture along the boundary; 

 coronoid bone (attached to the articular) evident. Species carnivorous. Esocid.f., xciv. 

 aa. Third superior pharyngeal greatly enlarged, covered with bluntish, tricuspid teeth ; fourth 

 superior pharyngeal wanting or fused with the third; lower pharyngeals large, fused 

 into a thick triangular bone with transversely concave surface, covered with blunt, 

 tricuspid teeth; teeth in jaws always small, conic, or tricuspid; maxillary close to pre- 

 maxillary, but not suturally joined to it, there being some open space between; coro- 

 noid bone small, but present ; no canine teeth; no zygapophyses to the vertebra^. 

 b. Third superior pharyngeal solidly joined with its fellow to form an ovoid plate, which 

 sends two processes forward; cleft of mouth narrow; the lower jaw usually pro- 

 duced; teeth of jaws tri<uspid; herbivorous species. Hemiramphid.k, xcv. 

 bb. Third superior pharyngeals more or less closely appressed, but not united; species at 

 least partly carnivorous. 



♦With this order begins the series of families in which the air duct of the air bladder disap- 

 pears in the adult condition. These form the group or series known as Pliysoclyili, iu contra- 

 distinction to the Phj/sostomi, in which the air duct is persistent. To the PAi/so8(omi belong the 

 Otlwriophyii, Apodes, Iso$poHdyli, Uaplomi, etc. 



