124 DR. RICHARDSON'S DESCRIPTION OF AUSTRALIAN FISH. 



tlie mouth has a form intermediate between Dajaus monticola and the typical Mullets, 

 without any other vestige of the mesial keel on the lower jaw, tongue and isthmus, than 

 the thin fold of integument which separates the lower pharyngeal plates. If, there- 

 fore, Dajaus is to be retained as a separate group, this Van Diemen's Land fish seems 

 to belong properly to it. Dajaus monticola, the only previously described species, in- 

 habits the fresh waters of the Caribbee Islands, near to their sources, but we are not 

 informed whether it visits the sea or not. Dajaus Diemensis is taken in the sea that 

 washes the shores of Tasman's peninsula in Van Diemen's Land. Mr. Lempriere has 

 furnished me with no other information respecting it, than that it is highly esteemed 

 as an article of food, and that the specimen described below is of the usual size. The 

 ' Histoire des Poissons ' mentions three Mullets from New Holland and one from New 

 Zealand. Two of them, Mugil Peronii and M. acutus, have keeled tongues, only two 

 pyloric caeca, and the ascending branch of the stomach cylindrical. The latter has also 

 a more acute snout than is usual in Mullets. Mugil Ferrandi, from Port Jackson, has 

 a keel in the middle of the otherwise flat tongue, and a black stripe in the axilla of the 

 pectoral, with another tipping the caudal fin. None of these correspond with our Da- 

 jaus in the number of their rays. The Mugil Forsteri of New Zealand is figured with an 

 acute snout ; and the little that is known of it does not agree with the Tasmanian fish, 

 which Mr. Darwin has shown to range as far as King George's Sound, on the west coast 

 of Australia. 



Form. — Elongated, compressed ; the curvature of the back moderate, and somewhat 

 less than that of the belly. The greatest height of the body is one-fifth of the whole 

 length, caudal included. At the nape the height is one-fourth less than under the spi- 

 nous dorsal, and the height of the tail behind the anal is less than half that of the body. 

 The breadth is greatest at the shoulder, and from thence it diminishes imperceptibly to 

 the caudal tin, that of the back being throughout greater than that of the belly, though 

 the latter is flattened for a small space before the ventrals. 



The head is flatly rounded above, like the back, and it diminishes in thickness to the 

 end of the snout, which is half the width of the nape, and is very obtuse, almost trun- 

 cated. There is a considerable notch between the nasal bones, which in the recent fish 

 is filled by integument stretched evenly across. The lips have very little development 

 on the intermaxillaries or lower jaw ; but the sides of the mouth, when distended, are 

 largely closed by membrane, within which the labial plays, not reaching the margin of 

 the orifice. The intermaxillaries have considerable protractility, and the lips which 

 cover them being widest towards the symphysis, they press back the soft integument 

 of the snout in a very sUghtly lunated manner when the mouth is closed. The lower 

 jaw then shuts in beneath the intermaxillaries, the commissure being a segment of a 

 circle. When the mouth is fully extended, its orifice, viewed in front, represents a semi- 

 elhptical arch, the lower jaw being a transverse chord. The intermaxillary widens ex- 

 teriorly into a thin plate, which is deeply notched posteriorly, and recedes a little from 



