72 SHELL GALLEKY. 



Case A, Plumatella repens* (Fig. 22) forms brown branching colonies, 



uprigM wholly or partly adherent to the surface of leaves of water plants, old 



^ ^ ' wood, etc. The individual cells are club-shaped, and about a quarter 



of an inch long, each cell being attached to the upper back part of 



the cell below ; the statoblasts (Fig 21, B) are simple oval bodies 



with a zone of air cells. 



Plumatella {Alcyonelld) fungosa forms thick masses, composed of 

 closely packed vertical tubes. A small specimen * surrounding a 

 stick from Hampstead Ponds is exhibited, and also a slice of another 

 specimen, prepared and presented by Mr. C. F. Eousselet, showing 

 the polypides expanded. 



Lophopus crystallinus* occurs in the form of translucent gelatinous 

 blobs, often attached to the slender stems of duck-weed. The 

 statoblasts (Fig. 21,0) are elliptical and pointed at each end. The 

 polypides are comparatively large, and can be easily observed through 

 the transparent surface. When its delicate plumes are fully expanded, 

 Lophopus forms a beautiful object. 



Cristafella mucedo* (Fig. 23) occurs in the form of greenish 

 translucent oval or worm-like colonies with the polypides on the 



Fig. 23. 



b 



Cristatella mueedo, creeping over a stem of water-weed ; x 6. (After Allman.) 



a, polypides with horseshoe-shaped crown of tentacles ; b, statoblasts seen 

 through the tissues ; c, muscular sole by means of which the animal creeps; 

 d, stem of water-weed. 



convex upper surface. The animal slowly creeps about on its 

 flattened under surface. 



Freshwater Polyzoa usually prefer dark places, but Cristafella 

 creeps along on the stones and pebbles in clear water, and in the 

 sunlight. The polypides form three or more concentric rows on the 



