668 



BR YOZOA—LOPHOPODA. 



Fig 7.— Lepeaih Pal- 

 LASIANA (magnified). 



the presence of the horny lid covering the tentacle sheath. A second order, 



the Cyclostomata (circular-mouthed), commonly form white circular or fan- 

 shaped stony crusts, plates, or branches, the component cells being tubular, 



and without horny lids. The tubes are frequently 



arranged in single or double rows. In a third 



order, the Ctenostomata (comb - mouthed), the 



colonies are horny or fleshy, never stony. When 



the tentacles are extruded, a comb-like circle 



of fine bristles is seen arising from the pro- 

 boscis near the base of the tentacles ; when the 



tentacles are retracted the bristles form a kind of 



operculum. The gelatinous Alcyonidium, so called 



from its resemblance to the zoophyte Alcyonium 



("dead men's fingers"), forms fleshy masses or long 



cylindrical branches. The polyps, which are em- 



b dded near the surface, extrude their tentacles 



when undisturbed. The Nit Coralline (Amathia 



lendigera) forma little dark brown bushy tufta, the 



ce'la being arranged on the branches in double rows of small horny cylinders 



like Pan's-pipes. 



The three orders above mentioned are included in one group, the 

 Infundibulata (infimdibidum, a funnel), in which the 

 tentacles form a funnel-like circle round the mouth. 

 The rest of the Bryozoa are included under the group 

 Lophopoda (crest foot), in which the tentacles are 

 arranged in a horse-shoe shaped zone round the mouth. 

 Nearly all the fresh-water Bryozoa belong to this group. 

 Lophopiis crystalUmis (Figs. 8, 9) is found in the form of 

 little jelly-like blobs on the stems of Duck-weed (Fig. 8). 

 The polypides can be seen aa yellowish red streaks in the 

 interior of a blob ; when the horae-shoe plumes of 

 tantacles are expanded the 

 animal presents a beautiful 

 appearance. Lophopiia and 

 other fresh-water Bryozoa 

 commonly propagate them- 

 selves by means of peculiar 

 internal buds, termed "stato- 

 blasts " (Fig. 10), which arise 

 in the cord passing from the 



stomach to the base of the cell. 



In Lophopus each statoblast is a flat, elliptical, 



seed-like bodyabout .f\j in. in diameter, pointed at 



each end, and with a dark-brown oval centre sur- 

 rounded by a broad band with a reticulate pattern. 



In the autumn the central part opens like a 



watch, and a young polypide half emerges and 



forms the nucleus of a colony. The remarkable 



Uristatella nntcedo forms pale-green worm-like 



colonies averaging about an inch in length 



and one-aixth of an inch in breadth ; the animal 



creeps about on the stems of water weeds. The polypides are arranged in 



Fiff. 8. — Lophopus 

 Urtstallinus on 

 duck-webd. 



fir/. 9.— LoPiiorua (macrnified) 



