On the Classification of the Order Synentognathi. 327 



the characters noted above ; parietals are present, but there is 

 no basisphenoid. Vertebrne 30 to 36 [Gamhusia 32, Belo- 

 nesox 36, Pcecilia, Mollienisia, and XiphopJiorus 30 or 31). 



The principal genera are Belonesox, Gamhusia, Petalo- 

 soi7ia, Glaridichthys^ Cnesterodon, Heterandria, Paecilia, 

 Girardinus, Acant/iophacehis, Phalloptychus, Phalloceros. 



In Belonesox tlie jaws are produced and tlie teeth cardi- 

 fortn ; some of the others are carnivorous and have the mouth 

 and dentition of a Fundulus, but these are closely related to 

 tliose mud-eating forms which have a small transverse mouth, 

 movable compressed teeth, and the rami of the lower jaw 

 loosely connected. All the species are American, ranging on 

 the coasts and in the rivers from the southern United States 

 to the La Plata, and especially abounding in Central America 

 and the West Indies. The males of some of the species are 

 among the smallest known fishes. 



EXPLANATION OF PLATE VIII. 



Goodea atripinnis. 



Fig. L Hjopcalatine and opercular bones (internal view), jml, palatine; 

 q, quadrate ; ms, mesopterygoid ; hvi, hyomandibular ; sy, sym- 

 plectic ; oj), operculum ; sop, suboperculiim ; top, i)iteroperculum. 



Fig. 2. Pectoral arch (except post-temporal and supra-cleitbrum). cl, 

 cleithrum ; ^x7, post-cleithrum ; sc, hypercoracoid ; cor, hypo- 

 coracoid ; r, radials. 



Figs. 3-5. Skull : 3, from behind ; 4, from above ; 5, from below, soc, 

 supraoccipital ; hoc, basioccipital ; eoc, exoccipital ; epo, epiotic ; 

 opo, opisthotic ; spo, sphenotic ; pto, pterotic ; pro, pro-otic ; 

 asp, alisphenoid ; psp, parasphenoid ; v, vomer ; eth, meseth- 

 moid ; leth, lateral ethmoid ; n, nasal ; por, praeorbital ; /, fron- 

 tal ; p, parietal ; pit, post-temporal. 



XXXVI. — The Classification of the Teleostean Fishes of the 

 Order Synentognathi. By C. Tate Regan, M.A. 



(Published by permission of the Trustees of the British Museum.) 



[Plate IX.] 



The order Synentognathi (Pharyngognathi malacopterygii 

 of Johannes Miiller) may be shortly diagnosed as comprising 

 malacopterous physoclists with the lower pharyngeals com- 

 pletely nnited. In these fishes the dorsal fin is placed far 

 back, above the anal, the branched rays of the caudal are 

 only 13 in number, the pectorals are placed high, and the 



