138 FRESH-WATER EHIZOPODS OF NORTH AMERICA. 



reproduction of the shell-covered rhizopods in general, but up to the pres- 

 ent time I have been disappointed. Among the multitude of specimens 

 I have seen I never observed a pair in the position which is commonly 

 viewed as that of conjugation, and regarded as having some relation with 

 reproduction. 



HYALOSPHENIA TINCTA. 



Plate XX, figs. 11-18. 



Shell compressed pyriform, variable in the relation of breadth to 

 length ; in transverse section compressed oval ; composed of pale yellow, 

 transparent, structureless, chitinoid membrane ; mouth transversely oval. 

 Sarcode colorless ; pseudopods digitate, usually two, three, or more. 



Size — Smallest specimen, 0.076 mm. long, 0.056 mm. broad, 0.028 

 mm. thick, with the mouth 0.02 mm. by 0.008 mm. ; second specimen 

 broader than long, 0.06 mm. long, 0.08 mm. broad, with the mouth as in 

 the former ; third specimen, 0.08 mm. long and broad, 0.036 mm. thick, 

 and mouth same as in former; largest specimen, 0.092 mm. long, 0.064 

 broad, and mouth as in the others. 



Locality. — Abundant in the sphagnous swamps of Tobyhanna, Pocono 

 Mountain, Monroe County, Pennsylvania ; found also in the sphagnum 

 near Kirkwood station, on the Camden and Atlantic railway, New Jersey. 



Hyalosphenia tincta, figs. 11-18, pi. XX, is closely related with 

 H. cuneata, but from its more pyriform shape, pale tinted shell, and living 

 in sphagnum instead of ponds, I have regarded it as distinct. 



The shell is compressed pyriform, with a very short neck, usually with 

 little difference between the length and breadth. It is composed of pale 

 yellow or straw-colored transparent chitinoid membrane, without trace of 

 definite structure. It is thicker than in H. cuneata, and is therefore less 

 flexible. At the lateral borders, usually below the middle, it presents a 

 pair of minute pores for the ingress and egress of water. Sometimes 

 another pair of similar pores are found along the same border above the 

 middle. See figs. 11, 12, 14, 16, 18. 



In transverse section, the shell is laterally compressed oval, with 

 obtusely rounded poles. The mouth has the same form, and is slightly 

 directed upwardly toward the commissures. 



The size of the shell differs but little, though there is considerable 



