492 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
out that it cannot be a Conis , for it has no double crown of tentacles 
bearing ocelli on the shorter and upper of these bodies. Weismann 
supposed that it was a deep-sea form, but Dr. Zoia’s specimens came 
from water of inconsiderable depth. 
Porifera. 
Sponge-remains in Lower Tertiary Strata of New Zealand.* — Dr. 
G. J. Hinde and Mr. W. M. Holmes have examined the sponge-remains 
from beds of siliceous or siliceo-calcareous material found near Oamaru, 
South Island, N.Z. It is the same deposit as that which contained the 
diatoms described by Messrs. Grove and Short in the Journal of the 
Quekett Microscopical Club for 1886 and 1887. 
The probable number of genera and species of the different divisions 
of siliceous sponges is — 
Monactinellid, 70 species and 24 genera ; 
Tetractinellid, 22 „ 9 „ 
Lithistid, 7 „ 5 „ 
Hexactinellid, 11 „ 5 „ 
but, of course, this estimate falls far short of the real number present. 
Nearly every hitherto known form of spicule of siliceous marine Sponge, 
both skeletal and flesh-spicules, is represented in the Oamaru deposit, 
if we except some of those from Palseozoic strata and a few of recent 
sponges. While the detached spicules appear to mostly belong to still 
existing genera, the species appear to be distinct from recent forms. As 
will be noted, there is a remarkable preponderance of Monactinellids ; 
this is very unusual if not exceptional, and the authors point out that it 
is due to the conditions by which the minute and delicate spicules of the 
Monactinellids have been preserved. It is not, therefore, unreasonable 
to suppose that the absence of these sponge-spicules in the older rocks 
is rather due to their having perished in the fossilization than that the 
Monactinellids did not coexist with those other groups whose remains 
have been partly preserved. 
Another important fact in this deposit is the association of remains 
of what we must, from our present knowledge, regard as abyssal 
forms, with others whose relations now exist in comparatively shallow 
water. Some sponge-genera have, however, a very wide range in depth, 
and it is very probable that many Monactinellid genera now considered 
as only existing in shallow and moderately deep water will be found, on 
further investigation, to be equally capable of living in the same extreme 
depths as the more specially abyssal Hexactiuellids. The siliceous beds 
of Oamaru were probably formed at depths of not less than 1000-1500 
fathoms. 
Histology of Leucosolenia clathrus.t — Mr. E. A. Minchin describes 
the process by which the contractile ectodermal cells of this sponge pass 
from flattened expanded elements to contracted mushroom-like forms. 
The latter appearance is not found, however, in the cells which form the 
muscular sphincter of the osculum, or on the inside of the oscular 
margin ; the former case may be explained by the two layers of the 
* Journ. Linn. Soc. Lond,, xxiv. (1892) pp. 177-262 (9 pis.), 
t Zool. Anzeig., xv. (1892) pp. 180-4 (3 figs.). 
