160 



ILLINOIS 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 like those 

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



The following table gives various external measurements of six specimens 

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



Length in mm. 



Length of scolex 



(lateral view) 

 Length of bothrium 



Breadth of same 

 Thickness of same 

 Breadth of segment I, 



anteriorly 

 Breadth of same, 



posteriorly 

 Thickness of same, 



posteriorly 

 Maximum breadth in 



anterior part of 



strobila 

 Same in posterior part 



of strobila 



87 



0.87 



1.08 



0.75 



0.87 



Much 



contracted 



Ditto 



0.37 



1.01 

 1.11 



92 

 0.59 



0.77 



0.57 

 0.64 

 0.40 



0.53 

 0.38 



0.82 

 1.04 



29 



0.63 



1.00 



0.67 

 0.74 

 0.55 



0.74 

 0.52 



1.30 

 1.48 



72 



0.83 



1.01 



0.90 

 1.21 

 0.92 



1.16 



1.38 



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

 ment being about 2.6/x. Resting on a distinct basement membrane, well shown 

 after the use of Mallory'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, somewhat club-shaped pseudociha or "hairs "which constitute the 

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

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

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

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

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

 cuticula 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 hke those described by the writer (1914a:85) for Haplobothrium 

 glohuliforme, 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- 



