Report of the State Geolooisi, 



)'Z* 



Upon the mode of development and growth of the brachia and 

 supporting apparatus some importanl observations have been 

 made. 



Morse has shown thai in early stages of Terehratulina the 

 arms are simple or double horse-shoeshaped processes, quite like 



Rhynchospira (Homceospird) evcuc. 



Fig. 182.— The mature condition of the brachidium. 



Fig. 188 — The brachidium in a very early stage of growth; in this figure the form of the 



jugum is wholly constructive. (Beecher and Clarke.) 



the lophophore of the Bryozoa. The same author also demon- 

 strates that the formation of the crura and brachial supports is a 



Meristina Marin. 



Fig. 184.— Thel brachidium in a very Fig. 185. - The brachidium in a young shell, show- 

 early condition of growth ; showing the lax ing a distortion in one of the spirals caused by an 

 revolutions of thelribbon and the depressed obstruction to the peripheral growth on one side of 

 spiral cones. . the valves, which has apparently produced no dis- 



turbance of function in the brachia. 



gradual and permanent accretion, growth taking place on both 

 sides until union is effected and the support" thus completed. 



79 



