58 Cumings — Development of some Paleozoic Bryozoa. 



In many cases, as in Alcyonidium (fig. 37), Schizoporella 

 (fig. 39), Lepralia (fig. 36), and JSugula (fig. 41), one of the 

 lateral primary buds is suppressed. Where but one of the lateral 

 buds develops, it may be the right or left indifferently, as in 

 Alcyonidium (Barrois 1 ); or the right almost invariably, as in 

 Schizoporella. In Schizoporella the left lateral is sometimes 

 normally developed, but more often exists as a vestige or is 

 totally lacking. Both lateral buds are, according to Barrois, 

 never present together in Alcyonidium, but the indifferent posi- 

 tion of the lateral bud indicates that the plan is fundamentally 

 that of two lateral buds'. In Tuoulipora, according to Barrois' 

 interpretation, 1 3 (fig. 43) would be derived from 1 2 ; but from 

 the analogy of other Cyclostomata,* and from a careful study of 

 Barrois' figures, the writer is disposed to consider 1 2 and 1 3 as 

 in reality representing the two lateral buds. It will be seen 

 later to what extent the development of two lateral buds from 

 the protoecium prevails among all types of Ectoproctous Bry- 

 ozoa. The ananepiastic stage is quite similar for all. 



II. Development of Fenestella. 

 45 46 



Figures 44-46. — Primary budding stages of Fenestella coronis from the 

 Lower Helderberg (Shaly) limestones of Indian Ladder, New York. 



45. Top figure, protoecium (*) and one lateral bud (I) ; middle figure, pro- 

 toecium (*), one lateral bud and beginning of another (I, I) ; lower figure, 

 protoecium (*) and two lateral buds (I, I) ; 44. Protoecium (*), two lateral 

 buds (I 2 , I 3 ) and two buds of the second generation (II 2 and II 3 ) arising from 

 I 9 and I 3 ; 46. Protoecium (*) and buds of the 1st (Ii, I 2 , I3), 2d (II 2 , ll 3 , H31), 

 3d (III 2 , III3) and 4th generations (IV 2 , IV 3 ). 



All figures x 45. 



* Harmer 11 has shown that two sister buds are thus derived from the pro- 

 toecium in Lichenopora. 



