THE OPALINID CILIATE INFUSORIANS. 



41 



Form LATA, new. 



Type.—Vnited States National Museum Cat. No. 16430. 



Measurements. — Length of body 0.2 mm.; width of body 0.095 

 mm. ; length of nucleus 0.04 mm. ; width of nucleus 0.026 mm. ; length 

 of posterior process 0.062 mm.; cilia line interval, first individual, 

 anterior 0.0019 mm., posterior 0.0031 mm., second individual, anterior 

 0.0019 mm., posterior 0.0031 mm., third individual, anterior, 0.0018 

 mm., posterior 0.00357 mm. ; thickness of ectosarc 0.0161 mm. 



The nuclei in these swollen forms are often in active division. 



Fig. 18. — Protoopalixa caudata ; from Bombina pachtpa : a and 6 are specimens 



WHICH SHOULD PROBABLY BE CLASSED AS FORM LATA ; C AND d ARE CYSTS ; e, IS AN OPTI- 

 CAL TRANSVERSE SECTION OF A NUCLEUS IN AN ANAPHASE OF MITOSIS, SHOWING SIX MA- 

 CROCHROMOSOMES; 6 IS MAGNIFIED 460 DIAMETERS, THE OTHER FIGURES 1,000 DIAMETERS. 



Form ATTENUATA. new. 



Type. — United States National Museum Cat. No. 16431. 



Measurements. — Length of body 0.1543 mm.; width of body 0.024 

 mm. ; length of nucleus 0,0152 mm. ; width of nucleus 0.008 mm. ; 

 length of endospherule 0.002.; width of endospherule 0.0018 mm.; 

 cilia line interval, anterior 0.0025 mm., middle 0.0029 mm., posterior 

 0.003 mm. 



These slender individuals are much smaller than Protoopalina 

 caudata lata. In form they somewhat resemble P. intestinalis, but 

 83103—23 -4 



