Miscellaneous. 209 
(figs. 7 a,c, d of same tabula) are the forms which most resemble 
the recent shell in question, and are those which chiefly occur in the 
Red Crag other than that of Walton, though specimens of aluveolatus 
sometimes occur with them, which may have been lingering indivi- 
duals of the disappearing Walton form, or merely derivatives from 
destroyed sand banks of Walton age, mixed up with the increasing 
and prevailing forms, in consequence of that destruction and reac- 
cumulation of these banks which was proceeding throughout the 
formation of the oblique-bedded part of the Red Crag. 
I should not have troubled you with the subject had I not thought 
it likely that some one might point out the identity in question as 
an oversight of my father’s ; and having assisted him in all his sup- 
plements, and knowing his views about Murex erinaceus in the 
Crag, I wished to anticipate such criticism by explanation. If there 
were any conflict between his view and mine, I should entirely defer 
to his; but there is not, as he was not acquainted with the variety 
in question. 
In tab. iv. fig. 9, of the ‘Crag Mollusca,’ is represented a full- 
grown shell with long open canal under the name of Murev tortuosus. 
This shell Dr. Jeffreys, in the list to Prof. Prestwich’s paper, by ex- 
press reference to the page of my father’s work describing it, assigns 
as “ Murex erinaccus, var.,” notwithstanding his statement in the 
4th vol. of the ‘ British Conchology’ (published four years previ- 
ously) that the genus Murea has the canal closed (“ covered over ”’), 
and his present assertion, that the closure of the canal distinguishes 
it from Purpura, and that the question of it “ involves a difference 
not merely of a specific but of a generic and even family character.” 
J. Sowerby’s original figure of M. tortwosus (Min. Conch. tab, 434) 
shows the canal wholly open, as does my father’s (and, I may add, 
as does every specimen of it that I have seen or can hear of); and 
my father’s description of it (Crag Moll. vol. 1. p. 40) is, “ canal 
contracted but open.” lan, &c., 
Szartes V. Woop. 
Aug. 17, 1883. 
A Social Heliozoan. 
Prof. Leidy exhibited drawings and made some remarks on a 
singular Heliozoan recently observed by him. His attention had 
been directed to it by Mr. Edward Potts, who discovered it, con- 
tained in considerable numbers in water, with vegetable débris, from 
Lake Hopatcong, N.J., where it had been obtained last autumn. 
The animal occurred mostly in groups composed of numerous indivi- 
duals. Oneof these groups, of irregular cylindroid shape, 0°84 millim. 
long by 0°36 millim. broad, was estimated to contain upwards of a 
hundred individuals. They reminded one of amass of tangled burs. 
' They remained nearly stationary even for twenty-four hours, and 
exhibited so little activity, that without careful scrutiny they might 
readily be taken for some inanimate structure. The individuals 
composing the groups appear to be connected together only by 
mutual attachment of their innumerable rays; and none were ob- 
Ann. & Mag. N. Hist. Ser. 5. Vol. xii. 15 
