160 



ILUNOIS BIOLOGICAL MONOGRAPHS 



[448 



mm., they were 1.31mm. in length by 0.82 in width. These measurements 

 are, however, of only relative value. Another strobila of the same age but con- 

 tracted at the time of fixation might show the same regions more Uke those 

 farther ahead and, thus, in alcohoUc specimens, evidently younger. 



The following table gives various external measurements of six specimens 

 in alcohol for the purpose of comparison; all dimensions are in milHmeters. 



The cuticula varies in thickness from 2 to 5m, the most common measure- 

 ment being about 2.6jLt. Resting on a distinct basement membrane, weU shown 

 after the use of MaUory's stain, it is divided into two strata of equal thickness 

 by a granular layer, the components of which seem to be related to the bases of 

 the stout, somevs'hat club-shaped pseudocUia or "hairs" which constitute the 

 outer moiety. WTiile the inner stratum was found to be homogeneous with 

 the stains used, the outer showed two intensities of color, an inner Ughter and 

 an outer darker. The former represents the narrowed central ends of the 

 spindle- or club-shaped pseudocilia, while the latter is determined by the well- 

 stained bodies of the cirri themselves. Linton (1901:473) said that "the 

 cutiaila is covered with minute spines," but Johnstone (1909:89) said, con- 

 cerning these structures: "I can see nothing of this kind in the species before 

 me. " All over the scolex and in the form of a band on- the posterior borders of 

 the proglottides (Fig. 103) these cirri become modified into stouter spinelets 

 from two or three times longer than elsewhere and everywhere directed pos- 

 teriorly, quite like those described by the writer (1914a :85) for Eaplobotkrium 

 globulijorme, but much longer relatively; thus indicating their function as 

 accessory organs of attachment. The largest spinelets are in the middle of 

 this band, those at the edges, that is in the anteroposterior direction, gradual- 



