112 THE SPONGES 0* GUERNSEY. 



sac-shaped organisms which swim freely by means of cilia. 

 They shortly settle down and develope into a sycandra-like 

 object, which in the case of the compound forms soon grows 

 and spreads over a large area. There is another form of repro- 

 duction seen in Tethya, a sponge resembling a Tangerine 

 orange. Small protuberances form, which, becoming stalked 

 after a time, break away and settle down elsewhere, there to 

 develope into a form like the parent. Most sponges also repro- 

 duce by budding, thus forming large colonies. 



Sponges are of great antiquity, being indeed amongst the 

 oldest organisms of our globe. As far back as the Silurian 

 period many genera are found, and it is generally believed that 

 flint nodules have been formed round a sponge nucleus. In 

 space as in time. Every part of the sea provides its quota, some 

 of them being of the most beautiful description — for example, 

 the lovely Venus' Flower Basket, so often seen in museums. 

 Alas ! our island coasts can boast of nothing so beautiful, but 

 the study of our lowly forms, both on the shore and at home, 

 will give a great deal of instruction and enjoyment. 



The Porifera love shelter, and it is under overhanging rocks 

 and in gullies, grottoes and caves between the tide-marks that 

 we must search for our specimens. The search will be short, 

 for it is a strange piece of coast-line that will not provide ;: few 

 species. Casual visitors to the beach cannot fail to notice three 

 distinct forms. One is the aforementioned Halicbondria or 

 Crumb of Bread sponge, which is green or red, and on being 

 broken reminds one forcibly of crumbly bread. The other two 

 are Grantia and Sycandra, both pure white, sac-like forms, the 

 former smooth and the latter spiky with projecting spicules. A 

 more diligent search will produce some remarkable species, 

 such as Pachymatisma, our largest sponge, which forms large 

 black lumps. I know of one at L'Islet that measures a foot by 

 six inches by over a foot in height. In a cranny well dow T n the 

 tide-range a piece of seeming black india-rubber may be espied. 

 This is Dercitus. Near by a lump of white crochet cotton may 

 attract the eye — it is Leucoselenia. 



An ancient oyster-shell kicked aside reveals its surface 

 perforated with numbers of holes. This is the work of a sponge 

 called Clione. The Tangerine orange has already been men- 

 tioned. From this short list it will be seen that sponges take 

 innumerable forms and their colours vary in like manner. 



The best hunting grounds I have found are at L'Islet, 

 Cobo, Bordeaux and Yazon. Alderney would richly repay a 

 searcher, and Sark also provides many specimens, the Gouliot 

 and other caves abounding with sponges. 



The following list has been compiled more with the idea of 

 forming a basis, unfortunately very fragmentary, for future work. 

 It contains 03 species, but I am convinced that this numbor could 



