GENUS HYALOSPHENIA— HYALOSPHENIA CUEEATA. 129 



HYALOSPHENIA CUNEATA. 



Plate XX, flgB.1-10. 



Hyaloaphmia ouneala. Stein : Sitzungsb. Bolim. Akad. Wissens. 1857. 



Diffiugia ligata. Tatem : Month. Micros. Jour, iv, 1870, 313, pi. Ixviii, fig. 1. 



Caikaria ligata. Leidy : Proc. Ac. Nat. Sc. 1874, 79. 



Syalosphmia lata. ScLulze: Aichiv mikr. Anat. xi, 1875, 335, Taf. xviii. Fig. 15, 18. — Archer: Quart. 



Jour. Mic. So. 1877, 110. 

 Eyalosphenia ligata. Leidy: Pr. Ac. Nat. So. 1875, 415; 1876,197. 



Shell compressed ovoid, with the narrower part conical and truncate 

 at the oral end, laterally and at the fundus convex ; mouth terminal, oval. 

 Shell composed of delicate, transparent, colorless, and structureless chiti- 

 noid membrane. Sarcode mass colorless, pyriform, and attached by threads 

 of ectosarc to the interior of the shell; pseudopods digitate, usually not 

 more than one or two. 



Sise. — Length 0.06 mm. to 0.076 mm. ; breadth 0.044 mm. to 0.06 mm. ; 

 thickness 0.02 mm ; breadth of mouth 0.016 mm. by 0.012 mm. 



Locality. — Lansdowne station spring, on Westchester railway, five 

 miles from Philadelphia. 



Hyalosphenia cniaeata, figs. 1-10, pi. XX, is compressed ovoid, and 

 in the view of the broader side presents a transversely convex fundus and 

 more or less tapering lateral borders, which may be plane, convex, or con- 

 cave in their descent to the mouth. The narrower view of the shell is also 

 obtusely rounded at the fundus and tapering at the sides. The mouth is 

 terminal and oval, with obtusely rounded commissures. 



The shell of H. cuneata consists of delicate, transparent, colorless 

 chitinoid membrane without trace of definite structure. It is sometimes 

 sufiiciently delicate to be bent by the tension of the threads of ectosarc 

 attached to it within. In one specimen, the broad sides of the fundus 

 appeared to be bent inward by the tension of these threads, as seen in the 

 lateral view, fig. 5. In another specimen, the tension of the threads 

 appeared to indent every point of attachment, as seen along the border 

 in fig. 1 . 



The size of the shell in several specimens ranged from ^^th to gi^th of 

 an inch in length, by ith to ^^ih of an inch in breadth, and about ^th of 

 an inch in thickness. The mouth measured about the ^^^ih. of an inch wide. 



9 EHIZ 



