74 ILLINOIS BIOLOGICAL MONOGRAPHS [362 



The cuticula, 5/x in thickness, consists of two layers of equal thickness, an 

 outer irregular and more darkly staining layer, which is sloughed off in many 

 places, and an inner, more homogeneous and lighter stratum between which 

 the outermost portion of the inner layer shows as a dark bounding membrane. 

 Altho only about one-half as thick on the outside of the scolex and still thinner 

 on the inside of the bothria, it is not modified to form minute spines on the 

 edges of the terminal disc nor hinder end of the scolex where such might be 

 expected to be located. Their absence also on the posterior borders of the 

 proglottides (cf. Haplobothrium glohuliforme) is not surprising since these pro- 

 trude only very slightly. The subcuticula varies from 40 to 50/i in thickness 

 and is made up of narrow elongated cylindrical cells with small nuclei, the outer 

 ends of which are dendritic and quite separate from each other as are the bodies 

 themselves. The meshes of the parenchyma are very loose and open, the spaces 

 being large and the strands of the cytoplasmic framework considerably nar- 

 rower than the small nuclei which are located as usual at the intersections but 

 surrounded by only a limited amount of protoplasm. Linton stated that, 

 "The segments contain numerous calcareous bodies, which exhibit a concen- 

 tric structure. " They are to be found fairly plentiful in all parts of the medulla 

 and cortex and even among the subcuticular cells. They are elliptical or 

 oval in outhne, the largest having dimensions of 18 by \2>n. 



The musculature of this species, excepting that of the scolex, is compara- 

 tively weak, no one series, not even the longitudinal, being especially strong. 

 All groups are prominent, in that they consist of more or less isolated fibres 

 quite diagrammatically arranged. Their conspicuousness is, indeed, amplified 

 by the fine texture of the parenchyma. The frontal or transverse series do 

 not form a compact layer closely applied to the inside of the longitudinal 

 muscles but, as shown in figure 83, a stratum of varying thickness; owing to the 

 degree of separation of the fibres, especially laterally. The myoblastic nuclei 

 of many of them can be easily seen. The sagittal series are, however, quite 

 prominent, and equally distributed from border to border of the strobila. 

 They show their myoblastic nuclei and surrounding cytoplasm very clearly, 

 reminding one of the dorsoventral muscles of Ahothrium rugosum. While the 

 fibres of both these series are only slightly more numerous opposite the posterior 

 borders of the proglottides, where they form more or less distinct septa, they 

 are very well developed in the neck and anterior segments. The longitudinal 

 muscles form only a single layer of loosely arranged fascicles of irregular size 

 in the middle and posterior segments, but in the neck they form a much thicker 

 stratum, showing no distinct bundles and occupying the whole of the space 

 between the transverse muscles and the subcuticular nuclei. Altho, as above 

 mentioned, the posterior borders of the proglottides are not very prominent, 

 there is a representative series of outer longitudinal muscles, best seen in the 

 middle segments where they are situated close to the longitudinal cuticular 

 fibres with which they are easily confused. Concerning the latter all that 

 need be said is that they are well developed and consist of isolated fibres which 

 render the two layers all the more visible. 



