262 ARCHER, ON MICRASTERIAS MAHABULESHWARENSIS. 
Bailey, apparently quite justifiable from his having seen 
“great numbers of each kind,” had more lately considered 
this form as distinct from Triploceras verticillatum, and it is 
described by him* under a distinct name, Triploceras gracile. 
It seems to me, then, that the characters of the body of the 
frond in both Bailey’s and Hobson’s forms are alike, and that 
the only difference lies in those of the terminal processes, 
which the latter in his description, without any more accu- 
rate explanation, merely alludes to as “of very peculiar 
form,” and as “differing greatly’ from those of Bailey’s 
form. Judging from the figures only, this difference seems 
to lie in the terminal processes of the former being some- 
what irregularly subdivided, instead of apparently rather re- 
gularly three-lobed ; but the lower end of Hobson’s figure is 
less irregular, and not quite like that of the upper. We 
have seen, indeed, that slight irregularities sometimes occur 
in many of these forms, and I must confess I hardly see 
grounds sufficient to retain Mr. Hobson’s name. My im- 
pression, then, is that both the Hong-Kong plant and Doci- 
dium Pristide (Hobson) will eventually turn out to be 
nothing else than Triploceras gracile (Bailey). Those, in- 
deed, who may not be disposed to acknowledge Triploceras as 
a genus well distinguished from Docidium, will call it rather 
Docidium gracile ; but, to my knowledge, not any forms yet 
described seem to show a transition or intermediate structure 
between the truncate extremities of Docidium (Bréb.) and 
the lobed extremities of Triploceras (Batley); and until such 
a species presents itself, so far as I can see as yet, the distinc- 
tions between the two genera seem to be sufficiently well 
founded to be maintained. 
* Toe: cit, p.'38: 
