390 On tie Anatomy &c. of the Symhranchoid Eeh. 



II. Eyes vestifrial ; gill-opening -wide, extending upwards above tlie 

 middle of the side ; teeth in a single series, minute on the prae- 

 maxillaries, well developed and obtusely conical on the palate and 

 lower jaw ; gills as in Sytnbninchus ; vertebrae about 100. 



3. Macroti'ema, gen. nov. 



Symhranchis includes three species from tlie fresli and 

 brackish waters of tropical countries — one from Central and 

 South America, another from West Africa, and the third from 

 the East Indies. Monopterus comprises a single species 

 widely distributed in the rivers of southern and eastern Asia. 

 Tlie new genus Macrotrema is established for Symhranclms 

 caJigans, Cant.^ which differs from Symbranchus not only in 

 structural characters, but in its smaller size and marine 

 habit. Cantor's type from Pinang, 200 mm, in total length, 

 is in the British Museum ; also a second specimen of 160 mm. 

 from Singapore. 



Family 2. Amphipnoidae. 



Amphipnons cuchia, from the fresh and brackish waters of 

 tropical Asia, differs from the Symbranchidte especially in 

 the development of a pair of respiratory sacs, diverticula of 

 the pharynx which lie on each side of the vertebral column 

 above the gills and between the skull and the pectoral arcli. 

 All the other features in which Amphipnons differs from the 

 Symbranchidfe, except the presence of scales on the bodv, 

 are connected with the presence of these sacs ; thus the skull 

 is shorter, the operculum and suboperculum are produced 

 backwards into very thin, almost membranous lamina, and 

 the pectoral arch is separated from the skull, with consequent 

 reduction or disappearance of the post-temporal. Gills are 

 developed on the second branchial arch only. The vertebrae 

 number 171 (106 + 65). 



EXPLANATION OF PLATE IX. 



J^/r/s. 1-4. Monopterus javanensis. 1, jaws, suspensoriam, and opercles ; 



2, skull from above; 3, skull from the side ; 4, skull from 



behind. 

 Figs. 5-8. Alabes dorsalis (5 and 6 x 2, 7 and 8 still more enlarged). 



5. skull from above ; 6, skull from below; 7, upper jaw ; 



8, lower jaw. 



^)»?.r, prfemaxillary ; »».r, maxillary ; deti, dentary : «;-, articulare : an, 

 angularc ; pa/, palatine ; pt, pterygoid ; q, quadrate ; mt, metapterygoid ; 

 Am, hyomandibular; s//, sympiectic ; pop, proeoperculum ; o/). operculum ; 

 sop, s\ibopt'rculum ; iop, interopercuUmi ; n, nasal ; eth, ethmoid : letfi, 

 lateral ethmoid; v, vomer; psp, parasphenoid ; /, frontal; p, parietal; 

 spo, sphenotic ; pfo, pterotic ; epo, epiotic ; pro, pro-otic ; soc, supra- 

 occipital ; eoc, exoccipital ; boc, basioccipital : t, temporal plate. 



