108 MARINE INVERTEBRATES 



and one or more large oscula occur on top. The color of the living 

 sponge is black. (Plates XXXIX, XL.) 



E. offipinalis, variety adriatica. More or less globose ; sometimes 

 attached by a broad base, sometimes by a short stem ; latter form more 

 or less club-shaped; oscula scattered over upper surface. Found in 

 the West Indies and the Mediterranean. (Plate XL.) 



E. offlcinalis, variety mollissima, the Levant toilet-sponge. Gener- 

 ally cup-shaped ; oscula on inner side of cup or on upper flat surface ; 

 very soft and elastic. 



E. offidnalis, variety rotunda. Usually massive; attached by a 

 broad base; sides vertical; oscula large and conspicuous on top, or 

 small in longitudinal rows on the sides. In the young this variety may 

 have a conical form with only one orifice, but later it has several oscula. 

 Its rotundity of form increases with the number of large orifices, but in 

 the adult stages the form varies, some being conical, while others have 

 the top divided into radiating ridges. 



E. offidnalis, variety dura. Irregular, massive, horizontally ex- 

 panded, with conical process on upper surface. 



GENUS Hippospongia 



H. equina. Some of the sponges of this species are massive, spheri- 

 cal, and attached by a small base ; others are horizontally expanded or 

 cake-shaped ; some have a depression in the upper surface and become 

 cup-shaped. 



H. equina, variety cerebriformis. Massive, circular, cake-shaped, 

 often depressed in the center, producing a cup-shape, attached by broad 

 base ; surface broken up by parallel longitudinal ridges having many 

 tufts. Cup-shaped forms predominate, and have a more or less rough 

 surface. This is one of the species known as grass-sponges. 



H. equina, variety meandriformis, the velvet sponge. The sur- 

 face of this variety has a protruding flattened cushion of fiber which 

 slightly resembles the convolutions of the brain-coral. Sometimes these 

 cushions are extended into long pencils. The oscula are large and 

 ragged on the edges ; the shape is irregular. The average size is seven 

 to eight inches in diameter. (Plate XL.) 



II. equina, variety elastica (variety agaricina, Hyatt), the yellow- 

 sponge. This is the second grade of commercial sponge, corresponding 

 to the Zimocca sponge of the Mediterranean. It is found growing with 

 the " sheepswool" in a depth of two to twenty feet, and is abundant. 

 It is massive and cake-shaped. The whole surface is a network covered 

 with numerous small, fine cones. (Plate XL.) 



The variety dura is classed with this species, which it resembles in 

 appearance, though it is harder in texture. 



H. canaliculdta. Massive, frondose ; more or less horizontally 

 expanded ; bears finger-like processes of varying development on the 

 upper surface. 



H. canallculata, variety gossypina, the sheepswool sponge. This is 

 the highest grade of the commercial bath-sponge. It is called "sheeps- 

 wool " because, perhaps, of its irregular shaggy surface. It is covered 

 with tufts, the larger oscula occupying the intervening depressions. 



