328 Mr. C. T. Regan on the 



pelvic fins are abdorainalj G-rayed. The scales arc tliiii and 

 cycloid, and the lateral line runs very low. The prae- 

 maxillaries are non- protractile and the inaxillaries enter the 

 border of the mouth to a greater or less extent ; the lower 

 jaw includes a sesamoid articulare, composed of a laminar 

 portion adherent to the inner face of the articulare, and of a 

 rather stout process which pi'ojects above the edge of the 

 jaw ; the hyo-palatine and opercular bones are normally- 

 developed ; the branchiostegals number from 9 to 15; the 

 more or less enlarged third upper ])haryngeals are denti- 

 gerous, opposed to the united lower piiaryngeals ; the fourth 

 are small or absent ; the upper surface of the cranium is 

 flatfish, without crests; the nasals are superior in position, 

 firmly united to the frontals and ethmoid; the upper edge 

 of the large praeorbitrd is attached to the outer edge of the 

 nasal, at right angles to the latter; the parietals, when 

 present, are very small, separated by the supraoccipital ; 

 there is no orbitosphenoid ; the well-separated alisphenoids 

 are not always recognizable as distinct elements; a basi- 

 sphenoid is present and the myodome has an osseous roof; 

 the opisthotic is absent, and the epiotic and pterotic are 

 produced backwards into a laminar expansion, with which a 

 similar projection of the exoccipital is usually united. The 

 post-temporal is usually simple, attached to the epiotic and 

 pterotic lamina, but there may be a very small inner fork 

 joining the exoccipital; the supra-cleithrum is reduced; the 

 sliort pectoral radials are rigidly united with the hyper- 

 coracoid and hypocoracoid, and the hitter is expanded ; there 

 is no mesocoracoid. The vi rtebrse are numerous, the centra 

 and arches are ankylosed, and the ribs and epipleurals are 

 inserted together on the transvere processes, the ribs com- 

 mencing on the third vertebra; the hypurals are reduced in 

 number and ankyloscd with the last centrum, which bears a 

 prominent horizontal ridge on each side. 



The Syuentognathi are an isolated group, without evident 

 close relationship to any other fishes, but showing certain 

 resemblances to the INIicrocyprini. The large number of 

 branchiostegals, the absence of spinous fin-rays, the truly 

 abdominal pelvic fins, the mouth-structure, and other cha- 

 racters indicate their derivation from malacopterous physo- 

 stomes ; they do not appear to be even remotely allied to the 

 Percesoces, which 1 am now disposed to unite with the 

 rercomorphi, for I cannot believe that two groups so pre- 

 cisely similar in their anatomy are not closely related, nor 

 that they have independently acquired the combination of a 

 spinous dorsal, 3 anal spines, 15 branched caudal rays, pelvic 

 fins anterior, of a spine and 5 soft rays, and 24 vertebrae. 



