28 Mr. C. T. Regan on the ' 



uniLcil witli tVoiitals ; subtemporal fossae very deep; no 

 Temporal depressions, but .supra-temporal fossie more or less 

 distinct, open behind, roofed by the post-temporal and some- 

 times by tlie pterotic and parietal. Cleithra normally sus- 

 pended from supra-cieithra. Air-bladder divided into two 

 parts by a constriction, ty|jically large and iVee, but sometimes 

 reduced {IHscognathu.i^ Gynnochilns), or the anterior part 

 sometimes enclosed m a bony capsule formed by the ossa 

 suspensoria y.Rhinogobio, Saurogohio). Outer ramus of os 

 susjMnsorium not connected with its fellow nor with the 

 transverse process of second vertebra. 



A fontanel is usually absent, but in Saurogohio it extends 

 from the supra-occipital to the ethmoid, except for the fronttil 

 bridge. 1 lie cupsule enclosincr the anterior part of the air- 

 bladder in lihinogobio is quite remote from the transverse 

 ])rocesses of the second vertebra and is widely open behind. 

 In Saurogohio the posterior aperture is reduced and there 

 are lateral exj)aiisions with terminal orifices whicb bear some 

 resemblance to those of the Cobilidte; in this case, however, 

 the transverse processes of the second vertebra are free 

 except near their base, where they support the lateral ex- 

 pansions, and the cavities of the latter do not communicate 

 with that of the capsule and apparently contain diverticula of 

 the paravertebral sacs. 



Tiiere are probably at least 1000 species known from North 

 America, Eurasia, and Africa. 



A satist;ictoiy classification of the genera cannot be arrived 

 at without nionographiiig the family, but the tollowing 

 remarks may not be out of place. 



The greatest variety of genera and species is found in Asia, 

 Avhich may be regarded as the original home of the group ; 

 and of all the genera which I have examined Opsarucht/ii/n 

 seems to bi'- the most i)rimitive. The terminal moutii, wide 

 gill-oj.enings, large i).-eudobranchia^, median dorsal fin, 

 rounded abdomen, triserial pharyngeal teelh, complete series 

 of circumorbitals, large posterior temporal fossae, and separate 

 second and third vertebifc are all features of generalization. 

 The foramen between quadrate and metaiiterygoid, so charac- 

 teristic of die Charaeitormes, is well developed in Oj^sari- 

 ic/it/rt/s -J this foramen is also present in C/icla, but is absent 

 in all 01 her C} prinids. In Opsariichihy.s the cleithra are 

 formed much as in typical Characiformes, narrowing forwards 

 to a point; many other genera with strongly decurved 

 lateral line — Barilius, JMiiio, &c. — agree with OpuariicJtt/tgs 

 in the form of the cleithra, rounded or pointed anteriorly, and 

 these are connected by genera such as Aspiut: with Leuco'Cus 



