for the Microscope. 95 



free. Spicules numerous, simple, needle-shaped, pointed at 

 both ends. The sponge is common. (PI. IX., fig. 48.) 



743. JOHNSTON'S SPONGE (Pachymatisma Johnstonia). 

 Sponge massive and undulating. Spicules stellate or three- 

 rayed, some spindle-shaped and minute. Found attached 

 to rocks. (PI. IX., fig. 28.) 



744. INCRUSTING SPONGE (Halichondria incrustans). 

 Sponge massive, with an uneven surface. Spicules of two 

 or three kinds, some slightly curved and spiny, others 

 slender and curved like an S. (PL IX., figs. 30, 32.) 



745. PLUMOSE SPONGE (Hymeniacedon pluinosa). 

 Sponge sessile, scarlet when alive. Spicules needle-shaped, 

 in bundles, and anchorate with angular hooks. Rare on 

 the Devonshire coast. (PL IX., fig. 29.) 



746. Tow SPONGE (Dictyocylindnts stuj>osus). Sponge 

 branching; branches slender and forked. Spicules needle- 

 shaped and cylindrical; those of the dermal membrane 

 stellate. The sponge is rare on the south coast. (PL IX., 

 fig. 46.) 



747. RIGID BRANCHED SPONGE (Dictyocylindrus ra- 

 mosus). Sponge branched in a variable manner, about 

 three inches high. Spicules needle-shaped, slender; some 

 pointed at one end, some at both, often flexuous; some 

 of them minutely spined. Sponge common. 



748. LATTICED SPONGE (Desmatidon agagropila). 

 Sponge sessile and irregular, red when alive, often in- 

 crusting seaweeds. Spicules of two or three kinds, al- 

 most club-shaped; others needle-shaped, and others two- 

 hooked or three-curved. 



749. FRAGILE SPONGE (Dysidea fragilis). Sponge, 

 when young, coating stones; afterwards in fan -like ridges, 

 and irregular. Skeleton coarsely reticulated, and without 

 spicules of its own, enclosing sand, &c. A section should 

 be examined for structure. 



750. PINK SPONGE (Isodidyafucorunf). Sponge sessile 

 and irregular. Pink or bright red when alive. The tex- 

 ture is delicate, and the spicules either needle-shaped or 

 hooked at both ends. Common around the coast. 



751. OYSTER-SHELL SPONGE (Cliona celata). Yellowish ; 



