Dr. F. A. Bather—Silurian Ophiurids of Australia. 318 
TV.—AUvstraLIAN PALONTOLOGISTS ON SILURIAN OPHIURIDS. 
By F. A. Barner, M.A., D.Se., F.G.S. 
OME interesting Ophiurids from the Melbournian rocks of Victoria 
are described by Mr. F. Chapman in Part viii of his valuable 
series of articles on ‘‘ New or little-known Victorian fossils in the 
National Museum” [Melbourne] (Proc. Roy. Soc. Victoria, n. ser., 
vol. xix, p. 21; Feb., 1907). 
First Mr. Chapman gives a fresh interpretation of the fossil originally 
described by Dr. J. W. Gregory as Protaster brisingoides (Guox. 
Mae., Dec. III, Vol. VI, p.24; 1889), and subsequently made by 
him the genotype of his new genus Sturtswra (Proc. Zool. Soc. London, 
1896, p. 1033; 1897). It appears that the fossil described by 
Dr. Gregory was an imprint in sandstone, and that the true structure 
is therefore revealed by a wax squeeze, now taken from a similar 
imprint. Thus, the ridge described by Dr. Gregory turns out to 
be a canal, and the ambulacral ossicles, instead of being subquadrate, 
are really boot-shaped, and, in the opinion of Mr. Chapman, closely 
approach those of Protaster biforts, Gregory. Mr. Chapman there- 
fore replaces the species in Protaster. The specimens studied by 
Dr. Gregory are in the British Museum (regd. E. 13000-—E. 18006). 
Since no holotype was definitely selected by Dr. Gregory, the original 
of his figures 1 and 2 (regd. E. 13000), is, with his concurrence, 
hereby selected. Examination of this and some of the other specimens 
enables me to confirm Mr. Chapman’s interpretation in a general way, 
though not as regards the precise shape of the ossicles. The paratypes 
of Protaster brisingoides (British Museum, E. 13001-6) probably 
include more than one species. 
Dr. Gregory also referred to his genus Sturtsura the species Protaster 
leptosoma, Salter. Mr. Chapman gives a diagram of the arm-structure 
in this species, based on a specimen from Leintwardine, in the 
National Museum, Melbourne; and in conformity with Dr. Gregory’s 
interpretation, he regards it as of distinct generic type from Protaster. 
He then proceeds to say that since Protaster brisingoides, the type of 
Sturtzura, proves after all to be a Protaster, therefore ‘‘ Sturtzura 
leptosoma, Salter sp., must now be regarded as the type form.” 
Mr. Chapman seems for the moment to have forgotten the perfectly 
definite, and, one had thought, universally accepted rule of nomen- 
clature, according to which the genus must follow its genotype. In 
other words, Sturtzwa must become a simple synonym of Protaster. 
The whole object of fixing on a genotype is to avoid the shifting of 
generic names, and Mr. Chapman’s action in taking Salter’s species as 
the type of Sturtzwra cannot be justified. If Protaster leptosoma, 
Salter, does not belong to Protaster, or to any other existing genus, 
anew name will have to be found for it. 
In describing a closely allied species, under the name Séurtzwra 
leptosomoides, Mr. Chapman merely quotes the genus as ‘‘ Sturtzura, 
Gregory, 1897” (which it no longer is), and makes no attempt to 
give a fresh diagnosis of it. Some doubt may, however, be cast on 
his interpretation of the two species which he refers to Sturtzura 
({Chapm. non Greg.). Thus, he applies the term ‘adambulacrals’ to 
