488 The Ohio Naturalist. [Vol. VI, No. 5, 



There is a difficulty in regard to the probable influence of the 

 .V and 2.V number of chromosomes in determining the gameto- 

 phvte and sporophyte generations, but the douV)le or half num- 

 ber of chromosomes may not be the important factor in deter- 

 mining the generation. The solution of the problem must rest 

 until the cytology of the tissues involved has l)een thoroughly 

 established. However these phenomena may be explained, they 

 must be regarded as only incidental deviations which have 

 arisen in plants belonging to a highh^ specialized group originally 

 possessing a typical alternation. The presence of apogamy and 

 apospory has nothing to do with the normal evolution of the 

 alternation of generations in the higher plants. 



A LIST OF ISOPODA FROM THE STATE OF OHIO, PRE- 

 SERVED IN THE MUSEUM OF THE CINCINNATI 

 SOCIETY OF NATURAL HISTORY. 



JOSUA LiNDAHL. 



This list was read at the Cleveland meeting of the Ohio Acad- 

 emv, in November, 1904, but was not turned over to the Secre- 

 tary for publication at the time. Now since we have such an 

 exceedingly good treatment of the subject in "A Monograph on 

 the Isopods of North America" by Harriet Richardson (Bull. 54, 

 U. S. N. M.) it appears appropriate to publish the list in the 

 Ohio Naturalist to encourage the search for more species in the 

 vState, as there surely must be more than I have collected. 

 Indiana has some species of Asellidae which are not in my list. 



Fam. Asellidae. 



Mancasellus macrourus Garman, Hamilton Co. 



Asellus communis Say, Hamilton Co., Sandusky (E. L. Mo.seley). 



Pam. Oniscidae. 



Cylisticus convexus De Geer, Hamilton Co., Springfield (Mrs. Eva 

 Engstroin), Columbus (H. Osborn). 



Porcellio laevis Latreille, Cincinnati. 



Porccllio rathkei Brandt, Hamilton Co., Springfield, Columljus (H. 

 Osborn). 



Porcellio scaber Latreille, Hamilton Co., vS|)ringfield. 



Metoponorthus pruinosus Brandt, Hamilton Co., Springfield, Colum- 

 bus (H. Osborn). 



Fam. .1 rmadillididae. 



Armadillidium vulgare (Latreille), Hamilton Co., vSjJringlield. 



The collection of Isopoda in the museum, comprising, at 

 present, 19 genera, 'MS species, has lately been revised by Dr. 

 Harriet Richardson, the eminent Carcinologist of the U. S. 

 National Museum in Washington. 



Cincinnati. 



