PORIFERA OF THE L..M.B.C. DISTRICT. 205 
Amphilectus incrustans is fairly plentiful at Puffin Island | 
where it is found encrusting the rocks at about low-water 
mark (April, 1889). The colour is straw-yellow, and a 
kind of meandering marking on its surface is very cha- 
racteristic. These markings seem to be caused by the 
alternate presence and absence of spicules. There are two 
kinds of megasclera: firstly tornote, measuring 0°19 mm. 
by 0°005 mm., which are found chiefly in the ectosome, 
and project with about half of their length beyond the 
ectoderm. And further: spined styli, measuring 07195 
mm. by 0°008 mm., which are found scattered irregularly 
through certain districts of the choanosome. The micro- 
cleres consist of palmate isochele (0°034 mm.) and simple 
sigmata (0.02 mm). I found also a few anisochele, but 
Tam not quite sure whether they belong to the sponge. 
Ceratose is present in a small amount and is best seen 
in very thin sections. The arrangement of the spicules 
is rather remarkable, as they are found only in certain 
tracts which stand at right angles to the surface. Alter- 
nating with those spiculated portions we find tracts of 
tissue which are quite devoid of spicules, and these latter 
tracts seem to be wider than the spiculated ones. The 
alternate arrangement of these tracts causes, I think, the 
meandering marking on the surface of the sponge. The 
diameter of the oscula is about 1 to 2-mim. 
A red coloured and elastic sponge which I collected at 
Port Erin, April, 1890, apparently belongs to the same 
species. 
Clathria seriata, Johuston. 
Halichondria seriata, Johnston. 
Spongia seriata, Grant. 
Chalina seriata, Bowerbank (vol. i., p. 376). 
Ophlitapsongia seriata, Bowerbank (vol. iii., p. 167). 
In my previous report, in giving the list of the Porifera 
recorded from the L.M.B.C. district, I placed the sponge 
