20 ILLINOIS BIOLOGICAL MONOGRAPHS [370 



of the genus Anoplocephala must of course be altered to conform; this 

 matter is taken up later on. 



Anoplocephala variabilis sp. nov. 



[Figures 18-24] 



This cestode has been found in Geomys bursarius, from Springfield, 

 Illinois, to Emerson, Manitoba ; as yet, no examinations have been made 

 south of this region. It seems to be wholly absent from the sandhill 

 regions; at Bemidji, Minnesota a few were found in hosts from very 

 wet, coarse sand mixed with humus, only a foot or so from the edge of 

 a swamp. In fertile soil, both uplands and bottoms, they vary in fre- 

 quency, being in some localities extremely abundant, and in others rare 

 or apparently absent. Not infrequently as many as fifty will be taken 

 from a single host; in one case 136 specimens of this and a species of 

 Hymenolepis were taken from one gopher. For distribution and fre- 

 quency, see the table on page 62. From this table it would seem proba- 

 ble that the range of this species is the same as that of its host tho it is 

 absent in many localities where its host occurs. The following descrip- 

 tion is based on well expanded specimens from central Illinois. 



The total length varies from 45 to 75 mm ; in life they can contract 

 to 20 mm. or possibly less. The proglottids number from 175 to 225, 

 the average of 19 specimens counted being 196. A neck is usually pres- 

 ent which is four-fifths the diameter of the head, and one-half to one 

 and one-half times as long, depending upon the stage of contraction. 

 The strobila increases gradually in width to the posterior end, being 

 there 2 to 3 mm. wide ; occasionally the last few proglottids become 

 narrower and longer. The first proglottids are very short. Distad 

 they lengthen rapidly, most of the proglottids being two-thirds as long 

 as broad. In several specimens especially in immature regions they 

 are longer than broad. This is true only in case of extreme expansion, 

 however. The scolex is irregularly oval in outline with sometimes a 

 suggestion of quadrilaterality. Ordinarily it is about 275/j, long by 300 

 to 400/a broad. It is distinctly set off from the neck by a deep circular 

 groove which however is not always apparent. The suckers stand out 

 rather prominently, due to the presence of longitudinal grooves between 

 them, the dorsal and ventral grooves being deepest and extending far- 

 thest distad. Opposite the anterior end of the suckers the dorsal and 

 ventral grooves arch over, the arches being as prominent as or more 

 prominent than the suckers. These arches are the ends of a transverse 

 bar which stands out prominently as the most anterior part of the 



