BY J. DOUGLAS OGILBY. 407 



A single median tuberculigerous suproral lamina developed 

 from the upper arch of the annular cartilage. Labial fringe 

 more or less conspicuous. Other characters similar to those of 

 the Order. 



Seven recent genera ai^e recognised as valid. 



Etymology : — nerpos, a stone ; fiv^uo), to suck ; in allusion 

 to the habit of clinging to stones and other substances by means 

 of the oral disk. 



Distribution: — Seas and fresh waters of the temperate 

 and subtropical regions of both hemispheres, four genera belong- 

 ing to the arctogsean and three to the austrogsean fauna, two of 

 which latter inhabit Australian waters. 



Analysis of the Australasian Genera. 



Body elongate and slender; head small; suctorial disk very 

 small, longer than broad, extending backwards midway to 

 the eye; outer lip present, continuous behind; surface of disk 

 plicated; no gular pouch; dental plates smooth; discal teeth 

 approximate; ventribasal plate of tongue usually tricuspid; 

 origin of first dorsal on the middle third of the body; head 

 and trunk with conspicuous series of open pores, forming on 

 the latter a well-marked lateral line ... 



Yelasia, p. 407. 



Body rather short and stout; head large; suctorial disk very 

 large, broader than long, extending backwards more than 

 midway to the eye; outer lip rudimentary; surface of disk 

 smooth; gular pouch present; dental plates grooved; discal 

 teeth widely separated; ventribasal plate of tongue bicuspid; 

 origin of the first dorsal on the last third of the body; no 

 series of pores on the head or trunk ... 



Geotria, p. 420. 

 Velasia. 



Velasia, Gray, Proc. Zool. Soc. London, 1851, p. 142. 

 Geotria, part. Giinther, Catal. Fish. viii. p. 508, 1870. 

 ? Neomordacia, Castelnau, Proc. Zool. & Acclim. Soc. Vict. i. 

 1872, p. 232. 



