166 PROCEEDINGS: BOSTON SOCIETY NATURAL HISTORY. 
and of Spencer has hIiowii tlu! value of a much closer discrimina- 
tion of characteristics. The large axillary interbrachials, the 
narrow ambulacral areas, and total lack of accessory ray- 
plates, show that the species belongs to the most primitive 
family among the Asterozoa, the Hudsonasteridae. It could be 
assigned to Hudsonaster, as defined by Schuchert, but the recent 
subdivision of that genus by Spencer makes it difficult to place 
a species generically unless both actinal and abactinal sides are 
preserved. 
Schuchert,' in his introduction, states: "Now that this study 
is finished, at least for the present, it is plain to the author 
that his species and genera are also in some cases too compre- 
hensive. The future student will restudy the specimens along 
with new material, and go more deeply into the detailed struc- 
ture of the parts." Spencer has already begun a restriction of 
the somewhat comprehensive genus Hudsonaster. Under 
the authority vested in the next investigator by the paragraph 
quoted, I am emboldened to advance certain suggestions which 
will, I hope, render somewhat simpler the disposition of such 
specimens as the one to be described here. 
The name Hudsonaster was proposed by Stiirtz- merely to 
relieve Palaeasterina of one of the numerous unrelated species 
which had been saddled upon it. It was improperly defined, 
and no well-preserved specimen of the type species, Palaeas- 
terina rugosa Bilhngs, has yet been found. Schuchert, however, 
saw that the type was closely allied to some of the simpler 
Ordovician starfishes, and redefined the genus, using facts 
drawn principally from Palaeaster incomptus Meek, which, how- 
ever, cannot, under the rules become the type of Hudsonaster 
Stiirtz, although it is that of Hudsonaster Schuchert. If the 
genus is to be subdivided, it is first of all necessary to restrict 
Hudsonaster to the original tj^pe, in which case, we shall, un- 
fortunately, know nothing of the actinal side except such 
inferences as may be drawn from its similarity to other species 
of Hudsonaster (sensu lata). The curious stellate plates of the 
abactinal surface furnish a generic character of some value, 
iBuU. U. S. Nat. Mus., 1915, no. 88, p. 10. 
=Verh. Naturh. Ver. Preuss. Rheinl., 1900, vol. 56, p. 224-225. 
