8 G-H Canadian Arctic Expedition, 1913-18 



anterior border of the anterior testis as far as the vitelline reservoir; the genital 

 sinus was a little shallower; the posterior end of the cirrus-sac reached to a 

 level behind the acetabulum about two-fifths of the distance from it to the 

 anterior testis; the ovary was almost exactly spherical rather than "trans- 

 versely oval"; but all of these differences are considered to be minor variations 

 and not of sufficient importance to affect the diagnosis of the species. 



Class II CESTODA 



Subclass CESTODA s. str. 



Order I Pseudophyllidea Carus 1863, nee Liihe 1910, nee Cooper 1919, e.p. 



Polyzootic, seldom monozootic, cestodes with mostly unarmed scolex with- 

 out rostellum or proboscis formation, excepting in the Haplobothriinae where the 

 prima ry scolex is provided with four protrusible proboscides resembling those of 

 the Trypanorhyncha. Usually with two weakly developed sucking grooves, which 

 in individual cases are modified by the strong development of their walls or by 

 more or less extensive fusion of their edges, so that they may appear funnel- 

 shaped or tubular, which may also unite with each other more or less completely 

 to form an unpaired terminal adhesive organ, or become rudimentary or entirely 

 absent, in which latter case they are replaced by a terminal functional organ of 

 attachment. The development of a pseudoscolcx takes place occasionally. No 

 headstalk (as in the Trypanorhyncha) . External segmentation more or less pro- 

 nounced in the cases of multiplicity of the genital organs, only seldom completely 

 absent. Genitalia in each segment usually single, seldom double. Their devel- 

 opment proceeds from ahead backwards only in their beginning and does not 

 continue to a degeneration of the reproductive glands; but the majority of the 

 proglottides, being at the same stage of ilcvelopment, bring their sexual products 

 to maturity at the same time, so that in all of them new eggs are formed continu- 

 ously and all the eggs of the whole animal are at the same stage of development. 

 A surficial opening of the uterus is always present. 



Testes numerous; vas deferens strongly coiled, without a true seminal 

 vesicle. Ovary near the posterior end of the proglottis, mostly median in the 

 case of single genitalia, seldom approaching the margin of the strobila bearing 

 the genital opening (that of the cirrus and vagina). Vitelline follicles very 

 numerous, mostly in the cortical, seldom in the medullary parenchyma. Uterus 

 a more or less winding canal, the individual coils of which converge somewhat 

 towards the centre of the proglottis to form the so-crJled rosette; but in other 

 forms it enlarges to form a capacious cavity, the uterus-sac, from which the 

 duct-like beginning of the uterus is sharply separated. Eggs operculate or non- 

 operculate, developing mostly only after being laid, but in other cases within 

 the uterus. 



This diagnosis of the order is that which I recently (1919:301) iDublished, 

 revised to include the family Caryophyllaeidae Liihe 1910, e.p. Cooper 1920, 

 which, after my study of Glaridacris catostomi, I agree with Liihe rightly belongs 

 to the Pseudophyllidea. 



Family I DIPHYLLOBOTHRIIDAE Liihe 1910, e.p. Cooper 1910 



Subfamily I LIGULINAE Liihe 1S99 



Genus Schistocephalus CrepHn 1829 



Schistocephalus solidus (0. F. ^Ililler 1776) 



For a synonymy and a diagnosis of this species sec Cooper, 1919: 318-29. 



Habitat. — The abdominal cavity of Pygosteus pimgilius L., a stickleback; 

 lake at Bernard harbour, July 15, 1915; C.A.E. Station -iOj. Only one worm 

 from each of two specimens of the host was taken. 



