21 
wliicli agree perfectly witli those of the Australian specimen I have before 
me. The general form of this specimen and the nature of its ribs are identical 
with those of European specimens. I have no doubt about the determination 
of this species. 
Horizon and Localities. — This Chonetes is very widespread in the 
upper beds of the Silurian of Europe and North America. Mr. Clarke has 
collected it in a compact slate from near Quedong, which is very analogous 
to some rocks in the Dudley District. 
Genus — LEPTA^NA, Batman. 
1. Lept^na quinquecostata, McCoy. 
Orthis quinquecostata, McCoy, 1846, Sil. Toss. Ireland, p. 33, pi. 3, fig. 
Leptcena ,, Idem, 1852, Brit. Pal. Foss., p. 236. 
,, ,, Salter, 1859, in Murchison’s Siluria, p. 211, fig. 8. 
,, ,, Davidson, 1871, Mon. Brit. Sil. Brach., p. 322, pi. 48, fig. 23-27. 
This little shell is perfectly recognisable when well preserved by means 
of the three, five, or seven small radiating ribs with which its surface is 
ornamented. These ribs sj^ring from the umbo, are almost equidistant, very 
thin and distinct from the other ornamentation of fine longitudinal striations. 
Mr. Clarke has collected hut a single specimen of this small species, 
and again this is an internal cast of the ventral valve; hut the specific 
characters I have just mentioned are so plain, that I do not think I am 
mistaken in the determination. To these characteristics are added those with 
which McCoy has made us acquainted, and which consist in the slight 
extent of the muscular impressions, of oval form and arranged on either 
side of the umbo, very oblique in reference to the longitudinal axis of 
the shell, and scarcely a millimetre long. 
Horizon and Localities. — In a greyish limestone at Yarralumla, 
associated with Stropliomenes peclen, Linn., and Letzia Salteri, Davidson. 
McCoy in the first instance discovered it in Ireland ; since then it has been 
recorded from Scotland and Kussia. 
