THE OPALINID CILIATE INFUSORIANS. 



149 



Measurements of an ordinary individual. — Length of body 0.232 

 mm. ; width of body 0.066 mm. ; thickness of body 0.056 mm. ; diam- 

 eter of nucleus 0.0035 mm. to 0.0043 mm. ; diameter of endospherule 

 0.001 mm. to 0.00132 mm.; cilia line interval, anterior 0.00132 mm., 

 middle 0.003 mm., posterior 0.00475 mm. 



This spindle-shaped Cepedea is somewhat dimidlata-like in form, 

 but it differs from the dididiata group in having a greatly developed 

 axial excretory vacuole. The much greater development of this 

 structure in this species and in the species madagascariensis, magna, 

 ohovoidea, glohosa, and haudinli, next to be described, seems to set 

 them apart from the dimidiata group, on the one hand, and from 

 the longa group, on the other hand. 



CEPEDEA MADAGASCARIENSIS, new species (figs. 114 and 115). 



Type. — United States National Museum Cat. No. 16514. 



Host. — MegalixaJus madagascariensis Dumeril and Bibron, one 

 infection, from United States National Museum specimen No. 33879, 

 26 mm. long, no date, no locality ; F. Werner, collector. 



Measurements: A, of a Tnediwrn-sized individual; B, of a large 

 individual — 



Measurements. 



Length of body 



Width of body 



Thickness of body: 



Anterior 



Middle 



Posterior 



Length of nucleus 



Width of nucleus 



Length of endospherule. 

 Width of endospherule. . 

 Cilia line interval: 



Anterior 



Middle 



Posterior 



TO771. 



0.513 

 .07 



.0055 

 .003 

 .0019 

 .0012 



.002 

 .003 

 .0036 



The shorter individuals of this species are often considerably flat- 

 tened, more so in front than behind. Others are very much elon- 

 gated and more slender. The species seems to form a transition from 

 the dimidiata-like forms to the longa-like forms on the one hand, 

 and to the Opalinas, on the other hand. This interpretation is con- 

 firmed by study of two other species parasitic in two of the Bufos, 

 Cepedea m/igna, a very slightly flattened form, and C. ohovoidea, 

 whose thickness is two-thirds of its width. 



Figure 114 shows the posterior, excretory pore, and portions of the 

 axial system of vacuoles. One sees that the endospherules are much 



