PORIFERA OF THE L.M.B.C, DISTRICT. 205 



Amphilecfus inci'usfaus is fairly plentiful at Puftin Island 

 where it is found encrusting the rocks at ahout 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 : fii'stly tornotee, measunng 019 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 0*195 

 mm. by 0"008 mm., wliich are found scattered irregularly 

 through certain districts of the choanosome. The micro- 

 cleres consist of palmate isochelse (0'034 mm.) and simple 

 sigmata (0.02 mm). I found also a few anisochekie, but 

 I am 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 v/hich 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 mm. 



A red coloured and elastic sponge which I collected at 

 Port Erin, April, 1890, apparently belongs to the same 

 species. 

 Clathria seriata, Johnston. 



Halichondria seriata, Johnston. 



Spongia seriata, Grant. 



Chalina seriata, Bowerbank (vol. ii,, p. 376). 



OphUto'psongia 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 



