OCCURRENCE OF STARFISH IN UPPER SILURIAN SERISS — ETHERIDGE. 129 
With Palasterina * * there is a resemblance in the quadrangular 
adambulacral ossicles bordering the ambulacra, but the difficulty 
is increased by the absence of certainty as to the presence or not 
of a second row of plates, Plasterina having but one row, whilst 
Palceocoma possesses two. At the same time there are unquestion- 
ably combs of spines along the edges of the ambulacra, which would 
favour the presence of a second row of plates as in the latter genus. 
Furthermore, the appearance of the disk is much more akin to 
that of Palceocoma than Palasterina , and on the whole it appears 
to me preferable to refer the Downing fossil to the former genus 
rather than to the latter. 
A difficulty now presents itself with regard to the name Palceo- 
coma. Salter proposed it in 1 857, f although D’Orbigny had 
previously suggested it| for the Lias Ophiura millleri , Phillips ; 
but, according to Zittel,§ even D’Orbigny’s name is in part a 
synonym of Ophioderma , M. & T. No other reference to this 
double use of Palceocoma , except that of the late Dr. Thomas 
Wright, || has come under my notice, not even in Dr. B. Stiirtz’s 
excellent review of “ Fossil and Living Starfish. ”1T 
Under these circumstances, and with the object of avoiding 
this confusion, I propose to substitute the name Sturtzaster for 
that of Palceocoma , Salter, in honour of Dr. B. Sturtz, of Berlin. 
To the present fossil I propose applying the specific name of 
mitchelli , and if therefore it be correctly referred to Palceocoma 
in the first instance, in the future it must be known as Sturtzaster 
mitchelli . 
The specimen is from the Upper Trilobite bed of the Wenlock 
Series at Bowning, N.S. Wales. 
In 1880, the late Prof. Alleyne Nicholson and the Writer pro- 
posed** the genus Tetraster to take the place of Palceaster , Salter 
(non. Hall), Salter’s conception of this genus being antagonistic to 
Hall’s later definition. ff More recently Dr. Sturtz has proposed,;}; J 
apparently for a similar reason, the name Salteraster in the same 
sense, and to which the date 1886 is attached; it is clear that our 
name has precedence. 
* Brit. Pal. Foss., Fas. i., 1851, p. 59; Salter — Ann Mag. Nat. Hist., 
(2), xx., 1857, p. 327. 
f Salter— Brit. Assoc. Beport 1856 (1857), pt. 2, p. 77; Ann. Mag. Nat. 
Hist., (2), xx., 1857, p. 327. 
J HOrbigny — Prodrome, 1850, i., p. 240. 
§ Zittel— Handb. Pal. i., Abth. 1, p. 445. 
|| Wright — Mon. Brit. Foss. Echinod. Oolitic Form., ii., 1, 1863, p. 29 ; 
Ibid., ii., 2, 1866, p. 143. 
*1T Sturtz — Verhandl. Nat. Yereins Bheinlande, L., 1893, p. 1. 
* Mon. Sil. Foss. Girvan in Ayreshire, 1880, pt. 3, p. 324. 
f Hall — 20th Ann. Beport N. York State Cabinet Nat. Hist., 1867, p. 
282. 
X Sturtz — Verhandl. Nat. Yereins Bheinlande, L., 1893, p. 42. 
