3396 



MOSS ANIMALS AND LAMP SHELLS 



round the two valves is often widened and contains small air chambers, or else horny 

 filaments which stand out radially and have barbed tips. This ring is termed the 

 swimming belt, and is a hydrostatic apparatus, which supports these winter buds or 

 statoblasts on the surface of the water. The complicated barbed hooks apparently 

 act as anchors, by means of which the passively swimming statoblasts catch on at 

 points suitable for their development during the course of the next spring As soon 

 as the time for development conies, the two valves split apart, and the germinal 

 mass emerges from between them. Here, then, we have an alternation of genera- 



a. Cristatella (double the natural size); b. STATOBLASTS OF Cristatella, WITH THREE YOUNG 



ANIMALS (enlarged). 



tions. Out of the winter buds and statoblasts asexually produced individuals arise, 

 which then reproduce themselves sexually, their descendants again yielding winter 

 germs. The colony produced from the winter buds may, however, continue for 

 some time to multiply sexually, but in autumn again produces statoblasts. These 

 processes taken together, namely, the growth of a Bryozoan colony by means of 

 the budding of one individual out of another, the detachment of the winter buds 

 in Paludicella, the formation of the statoblasts, and the appearance of eggs, well 

 illustrate the close connection existing between growth and reproduction. 



SUBCLASS Endoprocta 



Systematists have hitherto found themselves compelled to add to the Bryozoa, 

 or moss animals, certain genera whose most striking peculiarity is that the posterior 

 aperture of the alimentary canal lies within the tentacle crown. These have been 

 called Endoprocta, in contradistinction to the Bctoprocta, in which, as we have 

 seen, the aperture of the intestine (c in the illustration on p. 3391) lies outside the 

 tentacle crown. We take, as an example of the Endoprocta, the genus Loxosoma, 

 which might well be called the spoon animal, since, not only in Loxosoma cochlear, 

 represented in the illustration on p. 3397, but in most other species as well, the 

 side view, especially when the tentacles are withdrawn, strikingly recalls a ladle. 

 The body is attached to a stalk, and its anterior portion carries a circle of from 

 eight to twelve tentacles, provided with double rows of long cilia. The mouth is at 

 the lower edge of the disc which carries the feelers, while the posterior aperture 

 of the digestive tract lies somewhat above the middle of the disc. The thick stalk 



