400 MOXOGRAPH OF THE AUSTRALIAN MARSIPOBRANCHII, 



MORDACIA MORDAX. 



Petromyzon mordax, Richardson, Voy. Erebus & Terror, 

 Ichth. p. 62, pi. xxxviii. ff. 3-6* 1845. 



Mordacia mordax, G-ray, Proc. Zool. Soc. London, 1851, p. 239, 

 pi. iv. f. 61, and Catal. Chondropt. p. 144, pi. i. f. 6, 1851; 

 Giinther, Catal. Fish. p. 507, 1870; Klunzinger, Arch. f. 

 Natui'. xxxviii. 1872, p. 45, and Sitzb. Ak. Wien, Ixxx. 

 i. 1879, p. 429 (1880); Castelnau, Proc. Zool. & Acclim. 

 Soc. Yict. i. 1872, p. 229, and Edib. Fish. Yict. p. 17, 1873; 

 Macleay, Proc. Linn. Soc. N. S. Wales, vi. 1881, p. 382 ; 

 Johnston, Proc. Roy. Soc. Tas. 1882, p. 141 (1883;, and 1890, 

 p. 39 (1891); Stephens, Proc. Linn. Soc. N.S. Wales (2) 

 i. 1886, p. 506; Lucas, Proc. Roy. Soc. Vict. (2) ii, 1890, 

 p. 46. 



Short-headed Lamprey. 



Disk oval, its width when fully expanded somewhat less than 

 its length, its posterior margin reaching to or nearly to the level 

 of the eyes. Eyes conspicuous, the nasal tube opening a little in 

 advance of their anterior margins. The distance between the 

 extremity of the snout and the nasal opening is 21 to 26^ in the 

 total length and If to 2 in that preceding the first branchial 

 orifice, which is situated a little nearer to the last orifice than to 

 the tip of the snout; the space between the lastj orifice and the 

 extremity of the snout is 6i to 64 in the total length. Maxillary 

 plates widely separated; each plate is armed with three strong, 

 acute cusps, the tips of which are directed slightly backwai'ds; 

 they are arranged in the form of a triangle, having the apex in 



* Richardson's figure is unreliable, being taisen from a specimen in 

 which the lateral corneous lamellfe had been lost, a single papillary 

 prominence alone being left to represent each plate. 



t Copied from Richardson. 



+ In Richardson's description this measurement is erroneously given as 

 the space in front of theirs;' gill-opening. 



