0 
of tlio UnioiiicUe only have up to the present time been ilescTil)0(l from 
Australian and Tasmanian sedimentary deposits. Unio Dacomhli, M‘Coy, 
Avas discoA'cred in the Mesozoic Carhonaccous Series of the AAhannon IliA'cr, 
Victoria; hut I belieA'e only “ one doubtful specimen” exists.* * * § The other 
three forms are Tertiary species, one JJnlo TVilk'uisoni, Eth. jnr.,t from the 
Tertiary Deep Leads of Gnl^om^ ; the others from the Upper Tertiary beds 
of Launceston, Tasmania, viz., LTtiio Johmtonli, Eth., jnr.,| and Anodonta (^) 
Tamarensis, Eth., jnr. The forms from the Wianamatta Shales are certainly 
distinct from all of these. In Europe, ZTuio is usually regarded as character- 
istic of higher Jurassic beds, its place in the loAver series being taken by 
Cardlnia. Dr. A. \'on Klipstein, lioAAcver, has described under the name of 
(?) prohlematlcus,^ a shell from the Alpine St. Carsian Series (Upper 
Trias), having much the external appearance of a nasnte Unio. The earliest 
knoAvn form of this genus in tlic sedimentary rocks of North America, on 
Avhich any reliance can bo placed, is ZTnio Crisfonensis, Meek. In his most 
excellent paper, “A llevicAvof the Non-marine Eossil Mollnsca of North 
America,” II Dr. C. A. White says, “The earliest known members of that 
family^ noAv knoAvn to exist in North American strata are tAvo or three 
species, specimens of Avhich Avere collected by Professor E. D. Cope, in the 
valley of Gallinas Creek, Ncav Mexico, from strata Avhich he regarded as of 
Triassic age. These shells belong unquestionably to the genus Zhiio proper, 
as is shoAvn by the character of the hinge, and the muscular markings. . . 
One of these forms, . . . Avas described by Mr. Meek, under the name 
of ZT. Cristonensis There are some reasons for regarding the 
strata from Avhich these shells Avere obtained as of Jurassic instead of Triassic 
age ; but further iuA'estigation is needed before such an opinion can be 
confidently exjiressed . ’ ’ 
In the present case Ave sec the general outline of Zhiio, and the eroded 
beaks found in so many of its species. On the other hand, the nature of the 
hinge in these little shells is at present nnknoAvn. 
A second species, found by Mr. B. Dunstan, at BoAvral, approaches 
even closer in ontAAard form to some species of Zhiio than the present shell. 
It is described as Unio Dunstani. 
* Geological Survey Victoria, Progress Report, 1874, p. 24. 
t Unio Auddemdiem, var. Witkinxoni, Annual Report, Department of Mines, New Soutli AA'ales for 1S7S 
[1879], p. 168. T. .3, f. 5. 
t Papers anti Proc. R. Soc. Tasmania, for 1880 [1881] ; p. 18. 
§ Mittheil. Gebiete Geol. u. Pal., 1845, ii, p. 265, t. 17, f. 25 a and h. 
II Third Ann. Report U. S. Geol. Survey (Powell’s), 1881-2 [1883], p. 425, 
H i.e., the Unionidse. 
11a 124—88 
1 ) 
