36 On Suberites domuncula, Nardo. 
The ova of sponges in colour generally follow that of the 
parent sponges themselves, especially towards maturity, when 
this becomes more intense, and thus they contrast strongly 
with the rest of the substance. The ovabearing specimens 
which I possess are :—Halisarca lobularis, obtained from this 
shore in July 1874; Aplysina corneostellata, from Vigo Bay, 
by Saville Kent, F.L.S. &e., June 1870; Lsodictya simulans, 
from this shore (here the ovum is white), July 1874 (at this 
time also [found Esperta and Halichondria sanguinea nan ova- 
bearing state, but did not preserve any of them); lastly, 
Grantia compressa, trom this shore, May 1871, viz. those 
individuals which were successfully fed with indigo. Dr. 
Polgjaeff does not give the date of his observing the sperma- 
tozoa in Sycandra raphanus, although, from his paper having 
been read in the month of November, it may be inferred that 
this took place during the preceding summer. It is desirable 
to add the dates of such observations, because they may not 
only be a guide to others, but finally fix the period of this 
mode of reproduction in the species. 
EXPLANATION OF THE WOODCUTS. 
Fig. 1. Suberites domuncula, Nardo, natural size. Section of, showing :— 
aaa, sponge; 6b, cavities left by the lower whorls of the en- 
closed shell (Twrritella), which have disappeared ; c, remaining 
portion of the shell, covered with the ovigerous layer. 
Fig. 2, The same. Fragment of vertical section of ovigerous layer, 
showing :—a, convexities of capsules towards the sponge; 6, 
flat membrane covering the shell. Scale about 1-24th to 
1-1800th inch. 
Fig. 3, The same. Fragment of ovigerous layer viewed from the sponge 
side, showing the juxtaposition of the ova: a, ovum, on which 
the granulation of the surface is depicted. Same scale. 
Fig. 4. The same. Fragment of the granulated surface, much magnified. 
Scale about 1-24th to 1-GO00th inch. é 
