THE ENSOPBOCTOUS BRYOZOA. 



277 



described in 1741 by Trembley. In these "gullet-guarded" (Phylactolsemata) genera the epistome 

 is developed, and, as the arms of the lophophore are either free or suppressed, the tentacles usually 

 assume a "horseshoe-" or crescent-shaped crown, (Fig. 18, B.) This sub-order includes a number 

 of interesting forms, generally fungoid, gelatinous, limpid, or of a green, brown, or yellowish -white 

 colour. The majority are timid, light-shunning animals, and once disturbed are long before they 

 venture again to expand their tentacles. The wandering Cristatella (Fig. 17) forms an exception to 

 the rule, and seems capable of existing only in the full influence of sunlight in a whirlpool caused by 

 the ceaseless agitation of its constantly-expanded crown. The fresh-water 

 genera, to quote their chief historian, Dr. Allman, "may be sought in the 

 still and running waters of the land, in the broad river and the rushing 

 stream, in the pure cold mountain lake and the stagnant waters of the moory 

 fen. In interest they yield not one jot to their brethren of the sea, and 

 offer to the naturalist an inexhaustible source of gratification in the beauty 

 of their forms and the wonders of their organisation." 



THE ENDOPROCTA. 



In this secondary group of inferior Moss-animals the anal orifice occurs 

 within the tentacular crown instead of outside of it. In the single sub-order 

 Pedicellina the tentacles are developed from the two sides of the upper 

 margin of the cup-shaped cell. When at rest they lie partially concealed 

 within the vestibule, as there exists no sheath into which they could be re- 

 tracted. The animal does not leave the cell, and no muscles for its protru- 

 sion and retraction are developed. The ectocyst, or investing integument, is 

 soft throughout, remaining entirely unhardened by a secretion of a calcareous 

 or other nature. It closely surrounds the alimentary canal, and there is no 

 true body cavity. The animal chamber is seated on a long contractile stem, 

 from which it is generally separated by a diaphragm or partition. This 

 peduncle (Fig .29, p), sometimes furnished with spines, is very muscular towards 

 the base, and capable of vigorous movement. The various members of the 



colony are united by the creeping tube or 

 stolon (Fig. 28, s), from which the support- 

 ing peduncles spring at intervals. They 

 often swing to and fro so actively that the 



colony resembles " a field of corn agitated Fig. 28. BOWERBANKIA. 

 by the wind;" and the muscular move- M- *"<. Enlarged afterEincks.) 

 ments continue after the death of the 



,.,,., /. .v i i 11 



animal inhabitant of the cup-shaped cell 



at the free end of the stem, which periodically 



and is reproduced by internal budding. Besides 



Gizzard; z, 



intestine. 



Fumculus; int, 



Fig. 29. ENDOPROCTOUS TYPE 



PEDICELUNA CERNUA. (After Hincks.) 

 s, Stolon ; p.Ped uncle ; c, Cell ; t, Tentacles. 



falls away, 

 the marine 



Pedicellina, and a similar " urn-shaped " ( Urnatella) fresh-water 

 genus, this sub-order comprises a singular bi-sexual genus, the 

 only known solitary Moss-animal. It lives fixed by a pedal gland 

 the representative of the molluscan shell-gland attached to 

 ice)) the caudal extremity of worms and other marine animals. The 

 tentacles of Loxosoma are obliquely developed, and the body- 

 cavity is attached to a contractile stem without any intervening 



partition. It is also devoid of the creeping tube or stolon. 



ORDER PTEROBRANCHIATA. 



In the "mouth-footed" sub-order (Podostomata) the breathing organs arise from a winged or 

 divided base (Fig. 18, A), and the mouth of the Moss-animal is situated under an enormously-developed 

 organ, believed to be the equivalent of the " epistome " characterising the fresh-water genera. It 

 serves as a foot, enabling the animal to walk up the walls of its long and tubular cell, to which it 



