174 



DESIGN IN NATURE 



PLATE LXXII 



PLATE LXXII {continued) 



band whicla confers spiral movements on it. Illustrates the spiral action of the pedicle and the power of expanding and contracting 

 the body by centrifugal and centripetal movements. 



Fig. 21. — Adherent zooid {Scyphidia rugosa) in the expanded and contracted states, x 280 (Dujardin). Body pyriform, attached 

 posterior extremity most attenuate; integument furrowed obliquely and spirally in two directions; pharyngeal cleft prolonged. 

 Shows how spiral markings and structures are affected by centrifugal and centripetal movements (the Author). 



FicJ. 22. — Lorica or protecting sheath with two zooids (Cothurnia patula) in the contracted condition, x 200 (De Fromentel). 



Fig. 23. — Shows the same lorica and the same zooids (Fig. 22) in the extended condition. These figures illustrate in a striking 

 manner the centripetal and centrifugal movements of zooids (the Author). 



Figs. 24 and 25. — Two zooids {Cothurnia cohnii and Cothurnia pwpa), x 400 (Cobn and Eichwald), occupying elegantly shaped 

 lorica with annular transverse markings. At Fig. 24 the lorica is elongate ovate and subcylindrical ; the anterior margin being 

 abruptly truncated. At Fig. 25 the lorica is symmetrically ovate and widest in the middle. 



Fig. 26. — Colony stock of Opercularia stenostoma, x 200 (D'Udekem). Bodies elongate and pyriform, widest in middle and 

 tapering finely towards pedicle, which is small, rigid, and dichotomously divided. Peristome border and ciliary disc very narrow ; the 

 latter bearing an elegant single circlet of cilia. The general appearance is plant-like. The zooids are provided with remarkable 

 ciliated lids resembling those of the trap-door spiders. 



Fig. 27.— Adult colony stock of zooids {Zoothamnium carcini) in an inverted position, x 80. Illustrates branching distribution 

 of zooids. 



Fig. 28. — Terminal branchlet of colony stock of zooids {Carchesium epistylidis) as figured by H. E. Forrest, x 300. The zooids at 

 the left of the figure are expanded or open ; those at the right contracted or closed. Furnishes example of centrifugal and centripetal 

 movements. 



Fig. 29. — Termination of branchlet showing unilateral distribution of zooids {Carchesium polypinum), x 150. Figs. 28 and 29 

 jiresent a general flower-like appearance. 



