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ILLINOIS BIOLOGICAL MONOGRAPHS 



[482 



states that transverse divisions occured in B. infundibuliformis as well as in 

 B. proboscideus. Finally, as regards the external features, it should be noted 

 that the posteriormost, yet ripe proglottides of the smaller strobilas from the 

 fresh-water hosts are quadrate in shape, often as long as broad, and usually 

 somewhat narrower than the mature segments ahead. These, as stated by 

 Olsson (1893:17), show practically nothing more in the way of reproductive 

 organs than the lobed uterus-sacs. The following measurements of the scolex 

 are given for the sake of comparison: 



The anatomy of the species was studied by Matz (1892:110), later writers 

 referring to his work, altho Zschokke (1884:24), Lonnberg (1889:35) and Olsson 

 (1893:17) made some valuable contributions, while Liihe (1899a and 1900a) 

 dealt with it from a comparative standpoint. Most of them, however, con- 

 fined their attention almost entirely to the reproductive organs. 



The cuticula, from 4 to 5/.t in thickness, is divisible into two layers besides 

 the basement membrane, an outer and darker occupying about one-third of 

 the thickness of the whole, and quite smooth, and an inner, quite light layer. 

 It is slightly modified on the posterior borders of the segments to form minute 

 spinelets which are evidently formed by the sphtting of the somewhat thickened 

 outer layer. This modification is, however, not so well marked as in other 

 species. The subcuticula, from 60 to 100/i in thickness, extends from the 

 cuticula to the longitudinal muscles, thus occupying the outer one-half of the 

 cortex. Its nuclei are confined to its inner half, thus leaving the outer ends of 

 the cells free. The whole tissue requires good fixation and preservation to 

 show these features which in the older proglottides and longer strobilas are 

 otherwise affected by the general degeneration coincident with the development 

 of the enormous nimiber of eggs produced by this species. And it should be 

 stated here that this is more apphcable to the large marine form than to those 

 from fresh-water hosts. So far as the writer is aware no calcareous bodies 

 have been described for this species. They were found only in the smallest 

 strobilas with a maximum diameter of 15ju. The parenchyma is in the form 

 of a very fine reticulum, the spaces of which form the bulk of the tissue. 



Unlike A. rugosum the longitudinal muscles of the parenchyma are not 

 arranged in fasicles; nor do the transverse fibres form a septum between even 

 the anterior segments. The latter are often more numerous towards the pos- 

 terior end of the segments, as are the sagittal fibres, but they do not prevent 



