Asterolepis ornata, var. australis. 213 



arranged in a sub-parallel manner along the outer margins of the 

 shield, and in places along the sutures of the inner area, this 

 resulting in a particularly striking and ornate appearance. 



The specimens consist of the larger part of the cranial shield, only 



the anterior portion, comprising the orbital plates and parts of the 

 marginal plates, being wanting. The sutures, where visible, are 

 much the same in form and direction as in Phlyctaenaspis acadica, 

 Whiteaves sp., 1 with the exception that the sensory canals travers- 

 ing the external occipital plate from its outer posterior angles 

 extend farther into the cranial shield before meeting with that 

 coming down from the marginals. 



The tuberculatum in /'. acadica, whilst showing the same micro- 

 scopic characters, is much less dense than in either the Australian 

 species or variety. 



Measurements. — The type of P. australis, var. confertituber- 

 cztlata, has a total length of 59.25 mm. Its approximate width, 

 measured from the traces of the marginal plates, is about 69 mm. 

 The width inside the marginal plates is 47 mm. 



Distribution of Phlyctaenaspis. 



In his paper descriptive of Phlyctaenaspis, Dr. Traquair records' 2 

 two species of the genus, viz. — 



P. acadica. Whiteaves sp., from the Lower Devonian of Canada; 

 and P. anglica, Traquair, from the Cornstones (Lower Old Red Sand- 

 stone) of Herefordshire. 



Dr. A. S. Woodward records 1 ' an undetermined species of Phlyc- 

 taenaspis (recorded as Coccosfeus by Alth) from the Lower Devonian 

 ■of Russian Poland. 



To this we now add P. australis, McCoy, and the variety conferti- 

 tuberculata, nov., from the Middle Devonian of Buchan, Gippsland, 

 Victoria. 



From the above data we may infer that this genus made its 

 appearance in the Australian region at a later stage of the Devonian 

 than in Canada and England. 



1 Coccosteux acadicus. Canadian Naturalist (n.s.), vol. x., 1881, p. 94, woodcut. Whiteaves. 

 Trans. R. Soc. Canada, vol. vi., sect, iv., p. 9;;, woodcut, fig. 2, pi. ix. Phlyctaenaspis acadica, 

 Whiteaves sp., Traquair, Geol. Mag., vol. vii., 1890, p 55; pi. iii., figs. 1, 2. Idem, Annals Mag. Nat. 

 Hist., ser. vi., vol. xiv., 1894, p. 369 and woodcut. 



2 Geol. Mag., vol. vii., 1890, p. 60. 



3 Cat. Fogs. Fishes, Brit. Mus., pt. ii., 1891, p. 299. 



