178 ILLINOIS BIOLOGICAL MONOGRAPHS [466 



is represented by figure 35. Here the structure is likev^ise not embedded in 

 the wall of the pyloric cecum in which it is found but free in its lumen, the 

 anchorage for the strobila being obtained by the close approximation of the 

 mouth of the cecimi aroimd the narrow neck region and the concomitant 

 swelling of the more distal portions. Furthermore, the indications are that a 

 considerable portion of the anterior end of the strobila is involved in the 

 formation of the organ, especially since it is comparatively large. The final 

 stage is that shown in figure 36, where degeneration has gone on to such an 

 extent that there remains only a filamentous, homy or cartilaginous yellow 

 mass, deeply and firmly embedded in the wall of the cecum. Only the tip 

 is shown, there having been about 6mm. more to the region where it left the 

 host tissues and passed insensibly on to the anterior portion proper of the 

 strobDa. The latter showed only faint transverse wrinkles and no distinct 

 division into segments, as is seen, with some irregularity, however, in figure 32. 

 This form of pseudoscolex was foxmd, as described by Olsson, Linton and 

 Johnstone, to be surroimded by the tissue of the cecum degenerated to a 

 yellow waxy mass which, when freed from the surrounding tough tissue, 

 crumbled easily under the dissecting instruments. 



The strobila, at first almost cylindrical in shape, gradually becomes wider 

 and more depressed imtil the maximvim breadth near the posterior end is at- 

 tained. As regards the form of the segments Dujardin said that, ". . . le 

 reste du corps long de 100 a 140mm., large de 2mm. en avant et de 6.5 en 

 arriere, est Ubre dans I'intestin et forme d'articles tres courts, inegaux ou 

 dilates ca et la; . . ."; and Linton stated that, "The body is not dis- 

 tinctly segmented at first, but is crossed by innumerable fine wrinkles. " While 

 the latter statement is in the main true, and appUes particularly to the yoimgest 

 strobilas, many species show that these rugae, altho much obscured by irregular 

 longitudinal grooves, are simply due to the formation of extremely short seg- 

 ments which correspond proportionately vAth. the much more distinct ones 

 farther back. These segments gradually elongate as they pass backward 

 until the end proglottides are often quadrate or even longer than broad, depend- 

 ing on the degree of contraction or relaxation. Linton gave the length of the 

 segments near the middle of the strobila as from 0.7 to 1.0mm. and posteriorly 

 0.45, and the thickness as 2mm. The latter was 2.5mm. in the largest speci- 

 men examined by the writer. The openings of the uteri on the ventral surface 

 of the strobila form collectively a sort of shallow groove, more pronoimced, of 

 course, posteriorly but quite obliterated when the segments are considerably 

 relaxed. 



The anatomy of the species was first given careful attention by Linstow 

 (1889:235). Later Lonnberg (1891:75) and Matz (1892:113) published more 

 accurate descriptions to which most of the writers since have referred. That 

 of Lonnberg was foxmd, however, to be most applicable to the material at hand 

 from the cod and the pollack, for Matz was dealing with specimens from 

 Lota vulgaris and Linstow apparently confused the two possible species from 

 Lota and the marine Gadidae {inde infra). 



