SOME j^J^OETH AMEEICAN DESMIDIE^. 271 



EXPLANATION OF THE PLATES. 



a, a', a" = cellula vel semicellula a frontc visa. 

 ^> ^ = ,} „ „ vertice „ 



c = » „ „ latere „ 



d = semicellula a basi visa. 



Plate XII. 



Fig. 1, 2. Gonatozygon acnieafum, Hastings, forma minor. I, 400/1 ; 2, 520/1. 

 3-6. Phymatodocis Nordstedtiana, Wolle, forma minor, Boerg. 520/1. 

 7,8. Sp/i(Srozosma Auderiianum, West. 520/1. Two zygospores. 

 9. „ excavatum, Ralfs, var. 520/1. 



10. Spondylosium pulchrum, Arc}i.,va.r. inflatum. 520/1. 

 11.12. „ ,, „ xar. constrictum. 11, 170/1 ; 12, 520/1. 



13, 14. „ rectangulare, nobis. 520/1. 



15-17. Onychonema here, Nordst., var. micracanthum, Nordst. 15, IG, 520/1 ; 17, 400/1. 10 and 



17, two zygospores. 



18. „ „ „ var. latum, n. var. 520/1. 



19. Gymnozyga moniliformis, Ehrenb,, var. gracilescens, Nordst. 520/1. Zygospores. 

 20, 21. „ confervacea, n. sp. 520/1. 



22. „ delicatissima, Lagerli. 520/1. 



23. Desmidium aptogonum, Ereb., var. Ehrenbergii, Rabenh. 520/1. 



24. „ ,, „ 520/1. Zygospores. 



25. „ quadratum, Nordst. 520/1. 

 26, 27. „ cequale, n. sp. 520/1. 



2S. „ ,, „ 520/1. Zygospore. 



29. „ cylindricuni, Grev. 520/1. Zygospore. 



30. ,, „ ^, var, obliguum, n. var, 520/1. 



31. Ple7(rofcemum nodosum, Jj\uu\. Abnormal semicell. 170/1. 

 32j 33. Penium minutum, Cleve, var. gracile, Willc. 520/1. 



34. „ inconspicuum. West. 520/1. 



35. Docidium. baculum, Breb. 520/1. 



Plate XIII. 



Fig. 1. Pleurotanium hypocymatium, n. sp. 520 1. 



2, 3. „ subcoronulatum, West, var. detinn, n. var. 520 ]. 



4,5. „ trochiscum, n. sp. 520 1. 



6. „ Sceptrum, nobis, 520/1. 



7, 8, „ „ „ var, capitatum, West. 520/1. 



9-13. Triplocer as gracile, Bail. 9, 400 1 ; 10-13, 520/1. 



14,15. Closterium abruptum, West. 14,400/1; 15,520/1. Zygospores. 



16^ 17. „ Braunii, Reinsch. 16, extremity, 520/1 ; 17, portion of membrane. 830,1. 



18, 19. „ Cynthia, Not. 520/1. 



20-22. „ dilataimn, n. sp. 20, 21 , slO 1 ; 22, 220/1. 



23,24. ,, ro.s'i'fli'//?^, Corda, forma. 520,1. 



25,26. Cylindrocijstis angiilata,n. ^p. 520/1. 



27. Micrasterias arcuata, Hail., var. gracilis, u. var. 400/1. 



