188 Alo-ae 



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keys to the families, genera, and species, and copious references to 

 the more important literature dealing with matters of critical or es- 

 pecial interest, together with citations of numbered exsiccatae. The 

 18 plates contain 160 figures representing eharacteristic forms. 



The following are described as new: Cladophora gracilis f. aus- 

 tralis Collins; Dichotmnosiphon piisilhis Collins, from the West In- 

 dies; Spirogyra decimina var. submarina Collins, from New England. 



The following „new combinations" oecur: Conferva bombycina f. 

 tenuis (Hazen) Collins (Tribonema bombycina f. tenuis Hazen); Te- 

 traspora cylindvica var. extensa (Tilden) Collins (Tetraspora extenso, 

 Tilden); Chlorocystis DeBaryanum (Reinsch) Collins (Dactylococcus 

 DeBaryanus Reinsch); Codiolum gregarium f. intermedium (Foslie) 

 Collins {Codiolum intermedium Foslie); C. pusillum f. longipes (Fos- 

 lie) Collins (C. longipes Foslie); Tetraedron gracile var. tenue (Reinseh) 

 Collins (Polyedrium gracile var. tenue Reinsch); T. angulosum (Lar- 

 sen) Collins (Polyedrium angulosum Larsen); Sce>iedesmus bijuga 

 var. ßexuosus (Lemmermann) Collins (S. bijugatus var.ßexuosus Lem- 

 mermann); Crucigenia crucifera (Wolle) Collins (Staurogenia cruciata 

 Wolle); Ulothrix caldaria (Kütz.) Collins (Gloeotila caldaria Kütz.); U. 

 laetevirens (Kütz.) Collins (Schizogonium laetevirens Kütz.); Entero- 

 morpha prolifera var. arctica (J. Ag.) Collins (E. arctica J. Ag.); 

 Monostroma Grevillei var. lubricum (Kjellman) Collins (M. lubricum 

 Kjellmann); M. arcticum var. intestiniforme (Rosenv.) Collins (M. Gre- 

 villei var. intestiniforme Rosenv.); Diplochaete lamellosa (W. and G. 

 S. West) Collins {Polychaetophora lamellosa W. and G. S. West); D. 

 simplex (G. S. West) Collins (P. Simplex G. S. West); Chaetopeltis 

 americana (Snow) Collins (Ulvella americana Snow); Stigeoclonium 

 lubricum var. variaus (Hazen) Collins (Myxonema lubricum var. va- 

 rians Hazen); 5. ventricosum (Hazen) Collins (M. ventricosum Hazen); 

 »S. aestivale (Hazen) Collins (M. aestivale Hazen); S. glomeratu))i 

 (Hazen) Collins (M. glomeratum Hazen); 5. attenuatum (Hazen) Col- 

 lins (M. attenuatum Hazen); 5. staguafile (Hazen) Collins (31. stag- 

 natile Hazen); 5. minus (Hansg.) Collins (S. longipilus var. minus 

 Hansgirg) ; Gloeocystis sostericola (Farlow) Collins (Gloeocapsa sosteri- 

 cola Farlow) ; Herposteiron vermiculoides (Wolle) Collins (Apiian- 

 ochaete vermiculoides Wolle); Trentepohlia aurea var. Pittieri (De 

 Wildeman) Collins (T. Pittieri De Wildeman); ChaetomorpJia aerea 

 f. Linum (Fl. Dan.) Collins (Conferva Linum Harvey); Rhisoclonium 

 hieroglyphicum var. Hosfordü (Wolle) Collins (R. Hosfordii Wolle) ; 

 Spongomorpha duriuscida (Rupr.) Collins (Cladophora alaskana Col- 

 lins); 5. hystryx f. typica (Tönsson) Collins (Acrosiphonia hystrix f. 

 typica Jönsson); 6. hystrix f. littoralis (Jönsson) Collins (A. hystrix f. 

 littoralis Jönsson); 5. hystrix f. debilis (Rosenv.) Collins Cladophora 

 arcta f. debilis Rosenv.); 5. arcta f. conglutinata (Collins) Collins (C. 

 arcta f. conglutinata Collins); 5. saxatilis (Rupr.) Collins (C. saxatilis 

 Setchell and Gardner); 5. saxatilis var. Chamissonis (Rupr.) Collins 

 (C. Chamissonis Harv.); S. coalita (Rupr.) Collins (C. coalita P. B. A. 

 no. 319); Hormiscia Hartsii (Rosenv.) Collins (TJrospora Hartzii 

 Rosenv.); H. crassa l Rosenv.) Collins (U. crassa Rosenv.); H. incras- 

 sata (Kjellm.) Collins (U. incrassata Kjellm.); Acetabularia polyphy- 

 soides f. deltoidea (Howe) Collins (Acetabulum polyphysoides deltoi- 

 deum Howe); Acetabularia pusilla (Howe) Collins (Acetabuhim pusillum 

 Howe); Halimeda tridens f. typica (Barton) Collins (BF. incrassata f. 

 typica Barton); H. tridens f. tripartita (Barton) Collins (H. incrassata 

 f. tripartita Barton); Caulerpa crassifolia f. laxior (Weber) Collins (C. 

 piuuata f. laxior Weber); C. crassifolia f. pectinata (Kütz.) Collins 



