Hi 



figured on Plate XX., is very great. It is, however, rather 

 more compressed, and the scales are somewhat smaller, the 

 snout shorter, the eye large, so as exactly to equal the 

 breadth of the flat forehead between the edges of the 

 orbits, and the anal has a much slighter curve or notch. 

 The row of scales on the maxillary, being very deciduous, 

 has fallen from the specimens, and was omitted by the 

 artist in his drawing, but traces of it exist on the fish. 

 There are fifty-four scales, with tubes on the lateral line, 

 and five or six rows on the base of the caudal, making 

 about sixty in all between the gill-opening and caudal. 



Length 5j inches. 



Hab. The south-eastern and south-western coasts of 

 Australia. Norfolk Island. Port Jackson. King George's 

 Sound. 



Grystes macquariensis. Cuvier. 



Grysles mncquariensis, Cuv. et Viil. Hist, ties Poissons, iii. p. 58. 



Radii:— B. 7; D. 10|15, vel 11|1(5; A. 3|13; C. 18^; 

 P. 17, vel 19; V. 1|5. 



Plate LII I., figs. 8, 9, 



In Mitchell's Expeditions in Australia, PI. 6, f. 1 repre- 

 sents a fish locally named ' cod perch,' and to which the 

 author has given the specific name of Grystes peelii, be- 

 cause it varies in some respects from the description of G. 

 macquariensis in the Histoire des Poissons, and does not 

 correspond with Guerin's figure in the Iconographie de 

 Regne Animal. Our specimens have the pale margins to 

 the dorsal and anal, which exist in macquariensis, but 

 which peelii is said to want. Their form, however, is that 

 of Mitchell's fish, and as they agree sufficiently with the 

 detailed description in the Histoire des Poissons, the pro- 

 bability seems to be that macquariensis and peelii are but 

 one species, and that Guerin's figure, as in many other in- 

 stances, has been carelessly drawn. The account oi mac- 

 quariensis in the Histoire des Poissons is sufficiently 

 detailed ; and we shall merely add, that the scales are 

 small, deeply imbedded in a mucous skin, and cover almost 

 every part of the surface of the fish : they exist on the pec- 

 torals, ventrals, caudal and first dorsal, and entirely clothe 

 the second dorsal and anal. They are found, though mi- 

 nute, even on the membrane joining the limbs of the lower 

 jaw ; also on the gill-rays, snout, preorbitar, maxillary, 

 disk of the preoperculum, as well as on the gill-plates and 

 rest of the head. 



Mitchell desci'ibes the colour of peelii as being " light 

 yellow, covered with small, irregular, du.sky spots, which 

 get more confluent towards the back. The throat is pink- 

 ish, and the belly white." The original tints of our speci- 

 mens have been altered. 



Length from 6 inches to 18 inches. 



Hab. The Macquarrie, and several other Australian 

 rivers. 



Datxia elliptica, Richardson. 



Radii:— B. 6; D. 12|13; A. 3|8 ; C. 15^; P. 15; V. 1|5. 



Plate LII., figs. 4—8. 



At page 24, and in Plate XVIIL, fig. 3, 1 have described 

 and figured a fresh-water fish which differs from the group 

 of Therapon, Datnia, Pelates and Helotes, in having an 

 undivided air-bladder, and fi-om each of these genera in 

 some other peculiarity of structure. On the whole it agrees 

 best with Datnia. In Plate LII. we have given a repre- 

 sentation of another fresh-water species very similar to D. 

 caiidavittata of Plate XVIIL, but differing from it in its 

 more oblong form, its less elevated cheek and broader 

 operculum, which is covered by nine rows of scales. Its 

 teeth are villiform on both jaws, the outer row being a little 

 stronger, but still small. The teeth stand at the symphy- 

 sis about six or seven deep. There are none on the vomer 

 or palate bones. The prcorbitars are finely striated in 

 correspondence with minute marginal crenatures. The 

 preoperculum is strongly serrated at its rounded corner, 

 and becomes gradually less so towards the extremities of 

 both its limbs ; and the small, flat, opercular spines are 

 grooved at their tips so as to appear double. The hume- 

 ral bone and supra-axillary plate of the coracoid are fur- 

 rowed and crenated like the preorbitar. 



Length 65- inches. 



Hab. Rivers in Western Australia. 



Lethrinus cheysostomus. Richardson. 



Radii:— B. 6; D. 10|8; A. 3|8; C. 174; ?• ^ J V. 1|5. 



Nearly fifty species of Lethrinus are described in the 

 Histoire des Poissons, but as they are not characterised by 

 any well-marked peculiarities of structure, description fails 

 to convey such an idea of each species as will render it 

 easily recognizable. The comparative notices in that ex- 

 cellent work are chiefly of use when the ichthyological 

 student has a good series of specimens for his guide, but 

 do not suffice for the determination of isolated examples, 

 particularly when the colours of the fish have perished ; 

 and we have not access to more than seven or eight figures 

 which may help in this process. The specimen described 

 below was taken at Norfolk Island, and except as to colour, 

 which has doubtless changed by immersion in spirits, is in 

 excellent condition. In drawing up the description, I have 

 been very particular as to the position of the eye, and the 

 relative proportions of the parts of the head, especially in 

 regard to the dimensions of the preorbitar, whose size 

 greatly influences the physiognomy of the Lethrini. And I 

 have also attended to the teeth, that the species may be 

 the more easily identified when it is examined on the 

 coasts of Australia. 



The profile resembles that of genivittatus more nearly 



