116 BRYOZOA. 



in its course, and terminated by an anal orifice. When these 

 creatures are extended, the upper part of the body protrudes from 

 the cell ; the tentacular apparatus being supported on a kind of 

 neck, whereon the mouth (a) is easily seen, and near it the anus. 



On each side of the mouth the body divides into two arms, 

 which, when spread out, resemble a horse-shoe, being flattened and 

 blunt ; and upon the arms are arranged about a hundred slender, 

 transparent, and retractile tentacles, disposed on each side and 

 upon the summit, like the barbs of a feather ; and all covered with 

 an infinite number of cilia, whose action produces currents directed 

 towards the mouth, hurrying in that direction organized particles 

 contained in the water. 



The three individuals that thus inhabit the same general cover- 

 ing are produced at two distinct generations ; the two lateral 

 being the offspring of the central one, derived from it by a pro- 

 cess of gemmation, but, when complete, they are evidently quite se- 

 parate from and independent of their parent. 



(152.) From what is known concerning the propagation of the 

 Bryozoa, it would appear that their reproduction is effected in 

 several different ways. 



The most ordinary is by the developement of gemmae or buds, 

 that sprout from the parent stem in the branched species, or, as 

 in the Flustra and Eschara, are derived from the sides of con- 

 tiguous cells. 



A. second mode of increase is by the production of ciliated 

 gemmules capable of locomotion. These gemmules have been 

 attentively examined by Dr. Farre in the paper above alluded to, 

 and the nature of the ciliary action by which they are moved most 

 satisfactorily investigated, as we shall elsewhere have occasion to 

 notice more particularly ; but the organs wherein the reproductive 

 gemmules are developed are as yet undescribed. 



The Cristatella seems to be developed in an ovum, provided 

 with a shell of extremely singular construction. In fig. 47, 2, 

 the investment of one of these extraordinary eggs is represented 

 prior to the exclusion of the embryo Bryozoon, its natural size 

 being shown in the same figure (1): the external surface is 

 seen to be covered with numerous long processes arising perpen- 

 dicularly from it, and each terminates in a minute double hook, 

 adapted apparently to fix the egg upon marine plants at the sur- 

 face of the water : but how these hooks become developed is still a 

 mystery ; it would seem impossible that an ovum so formidably 



