EXPLANATION OF PLATE XXXVI. 



CARCHESIUM POLYPINUM, Linn, sp., vol. ii. p. 690. i, Adult colony-stock, 

 X 100 ; 2, a similar stock completely retracted ; 3, three colony-stocks 

 attached to a rootlet of Lemna, natural size, as delineated by Schaffer (1754) ; 

 4, termination of branchlet showing unilateral plan of disposition of the 

 zooids, X 150 ; 5, terminal branchlet with three zooids, showing independent 

 relationship of the contractile element of their respective pedicles, x 350 

 (after Stein) ; 6, fragment of pedicle, showing apparent transverse striation of 

 the central muscular cord, as delineated by H. E. Forrest ; 7 and 8, succes- 

 sive phases of longitudinal fission. 



9. ZOOTHAMNIUM NUTANS, C. & L., vol. ii. p. 698, x 2oo (Claparede & Lachmann). 



10. CARCHESIUM ASELLI, Eng., vol. ii. p. 693, x 125 (Engelmann). 



11. ZOOTHAMNIUM MARINUM, Meresch., vol. ii. p. 700, x 125 (Mereschkowsky). 



12-14. CARCHESIUM EPISTYLIDIS, C. & L.,vol. ii. p. 692. 12, Small colony-stock (after 

 Clap. & Lach.), x 300 ; 13 and 14, large colony-stock and terminal branchlet 

 of the same, as delineated by H. E. Forrest. 



15. ZOOTHAMNIUM NUTANS, C. & L., vol. ii. p. 698. Isolated zooid during contrac- 



tion, x 200 (Clap. & Lach.). 



1 6. ZOOTHAMNIUM AFFINE, Stein, vol. ii. p. 698, x 150 (Stein). 



17-20. ZOOTHAMNIUM SIMPLEX, S. K., vol. ii. p. 700. 17, Adult colony-stock, x 150; 

 1 8, retracted condition ; 19, isolated zooid, x 300 ; 20, conjugation of 

 migrant microzooid a with an ordinary sedentary animalcule. 



2i. CARCHESIUM LACHMANNI, S. K., vol. ii. p. 691, x 200 (Clap. & Lach.) 



22, 23. ZOOTHAMNIUM ALTERNANS, C. & L., vol. ii. p. 695. 22, Colony-stock with at 

 aaa subcylindrical microzooids, as observed by the author; 23, isolated 

 microzooid, X 400. 



24, 25. ZOOTHAMNIUM GLENISCUM, C. & L., vol. ii. p. 697. Expanded and contracted 

 zooids, x 200 (Clap. & Lach.). 



26. CARCHESIUM SPECTABILE, Ehr., vol. ii. p. 691. Colony-stock, as figured by Roscl 

 (1755), dimensions unrecorded. 



