July 1, 1899.] 



KNOWLEDGE 



147 



European zimocca sponge (5. ::imocca tijpica), which usually 

 assumes the form of round disks, convex below and flat 

 above, the waste-pipes opening on this flat upper surface. 

 In the West Indies and America the species is represented 



Fig. 2. — Grass-Sponge. Spongia officinalis punctata. 

 West Indies. 



by the hard-head and yellow sponges {S. dmocca corhsia). 

 In both these the shape is more or less loaf-like, with 

 the apertures of the waste-pipes distributed somewhat 

 irregularly over the upper surface. In the hard-head, the 

 general surface is fairly uniform, and the margins of the 

 apertures of the waste-pipes are distinctly produced. On 

 the other hand, in the yellow sponge (Fig. 3). the general 

 surface is traversed by a number of irregular fissures, and 

 the apertures of the waste-pipes are not producpd, the 

 whole appearance of this sponge being coral-like. None of 



Fig. 3. — Yellow Sponge. Spongia zimocca corlosia. 

 AVest Indies. 



these hard toilet-sponges bear a high value ; the price of 

 good samples of the West Indian varieties ranging from 

 about two to three shillings per pound at the wholesale 

 dealers. 



Much coarser, and of a totally different type of external 

 structure, are the bath-sponges of the genus Hipiio!:poniiia, 

 which are also common to the Mediterranean and the 

 American side of the Atlantic. Most'persons, if they gave 



any attention at all to the subject, would probably consider 

 that the large apertures in a bath-sponge correspond to the 

 oscula, or apertures of the waste-pipes, in a toilet-sponge, 

 and the smaller holes of the former to the pores of the 

 latter. Such a supposition would, however, be totally 

 incorrect, for, as a matter of fact, both the oscula and the 

 pores open on the surface of the tortuous tubes leading 

 from the large apertures into the body of the sponge. A 

 bath-sponge, therefore, really consists of complexly-folded 

 layers, with the system of incurrent and excurrent canals 

 in their thin walls. To the large apertures in sponges of 

 this type the name of pseudoscula is applied ; while the 

 twisting passages leading from them are known as vestibules. 

 The typical bath-sponge (Hijiposponnia equina t'/pica) is a 

 Mediterranean species, ranging from Eritra, opposite the 

 Island of Chios, to Tunisia, being represented by a very 

 coarse dark brown variety at Gibraltar. It attains to very 

 large dimensions, and its form and general appearance are 

 too well known to require description. In the trade it is 

 termed honeycomb sponge, and is sub-divided into bath 

 and toilet descriptions ; the two latter terms being thus 

 used in a different sense from their scientific application. 

 For large specimens of the best quality the wholesale price 

 ranges from ten shillings to twelve shillings and sixpence 

 each. 



On the other side of the Atlantic the ordinary bath- 

 sponge is replaced by a somewhat coarser variety known as 

 the wool-sponge {H. iijuiyia ;iossipina). The essential 

 feature of this sponge (Fig. i) is the production of the 



Fig. 4.- 



-Wool-Sponge. Sippospongia equina gossipina. 

 West Indies. 



free edges of the laminre into long tag-like processes, thus 

 giving to the whole a somewhat woolly appearance. It is of 

 inferior value to the European variety. Good samples of 

 these sponges reahse from eight shillings to eight shillings 

 and sixpence per pound. 



The last kind to be noticed is the West Indian velvet- 

 sponge (H. equina meandrina), which, although here 

 regarded as a race of the bath-sponge, is so distinct, as to 

 have considerable claims to rank as a species by itself. 

 Apart from the large "pseudoscula," this sponge (Fig. 5), 

 as its Latin name denotes, presents a considerable likeness 

 to the brain-coral. The pseudoscula are not only large, but 

 are also very numerous. Between these the edges of the 

 laminae are smooth and velvety, the intervening apertures 



