SEA LILIES, STARFISHES, ETC.—CLARK. 83 
a few dots or no markings at all. Diversity is equally 
marked in other features. The distance of the first arm- 
fork from the distal end of the radial shields ranges from 
.25 of the radial shield length to 1.10; or the same fact may 
be expressed in another way by saying there are from 9 to 15 
arm-joints in the undivided arm-base. The number of arm- 
divisions ranges from 6 to 10 or more. Most of the specimens 
show the radial shields well separated, and the disk has 
distinct interradial areas, but there is a tendency on the part 
of some individuals to have the radial shields united in pairs 
by thick, concealing skin and in such cases the interradial 
areas are much reduced ; thus the condition, characteristic of 
Conocladus, is approached. Further resemblance to Cono- 
cladus is brought about in certain specimens by the large size 
of the disk spines. In typical A. australis, these spines are 
about a millimeter high, conical, and the thickness at base 
about equals the height; they are present chiefly on the 
radial shields and are often confined to them ; in many speci- 
mens they are smaller and more numerous, and rarely they 
are reduced to low, inconspicuous tubercles. But in some 
cases, notably in some South Australian specimens, the spines 
are 1.5 mm. high and correspondingly stout. In these cases, 
too, the spines on the basal parts of the arms are larger than 
usual and the resemblance to Conocladus may be quite marked. 
Nevertheless none of the specimens have the radial shields 
completely united into five disk-wedges, with very much 
reduced interradial areas as in Conocladus, nor do any have 
spines on disk and arm-bases really as big as in that genus. 
For these reasons one can, without difficulty, separate speci- 
mens of the two genera, but Iam not sure that the separation 
is not an arbitrary rather than a natural one. I have previ- 
ously expressed the belief that Conocladus is derived from 
Astroconus, while Doderlein thinks the reverse to be the case. 
Which of us is correct can only be determined by a study of 
growth-changes in much younger specimens than any at 
present available. But the youngest specimens in the present 
series are not at all Conocladus-like, the radial shields being 
narrow and widely separated, the interradial areas large and 
the disk spines few and small. It is quite possible that further 
study and more abundant material will show that Conocladus 
oxyconus is only an extreme form of Astroconus australis, and 
not a separate species. In that case the genus Conocladus will 
need a new name, ?.e., the species amblyconus and microconus, 
for the name Conocladus will have to replace Astroconus as the 
generic name of Verrill’s Astrophyton australe, since it has the 
same type and antedates Astroconus by two years. In any 
case, whether C. oxyconus is specifically different from 
