82 Transactions of the Royal Canadian Institute, [vol. x. 



extensive. When greatly extended they appear somewhat thread-like 

 to the unaided eye, when contracted, during life or after preservation, 

 if no care has been taken to stretch the specimens, somewhat like a 

 string of fine beads, which characteristic has been incorporated in the 

 specific name. This is due anteriorly to the thickened hinder ends of the 

 foremost joints, while farther back it is caused by the uteri being greatly 

 distended with eggs. 



The largest specimens examined were two, 110 and 96 mm. in length, 

 containing respectively 59 and 55 proglottides. From uncleared material 

 the number of the latter is obtained by merely counting the joints for- 

 ward and depending on the distension of the uteri — the male and female 

 genital openings are very minute — in the hinder end of the strobila to 

 indicate the sets of reproductive organs, there being no other in evidence 

 of proglottidation in this region. 



The scolex is quite small, simple externally, and with the unaided eye 

 can scarcely be distinguished from the first joints. It is shaped roughly 

 like a rectangular solid, hollowed out laterally to form simple depressions 

 and dorso-ventrally the shallow bothria or organs of attachment. The 

 summit is som.ewhat prolonged as a low pyramidally shaped disc, quite 

 comparable to that ("Scheitelplatte") found in the members of the sub- 

 family Triaenophorinae Luehe, 1899. Furthermore, although to all 

 outward appearances this structure is unarmed, certain modifications of 

 the cuticle on the edges, as well as on those of the foremost proglottides, 

 to be described below, strongly remind one of the minute hooks with 

 which A7icistrocephalus microcephalns (Rud.) is provided. The opposite 

 end of the scolex is modified to form two pairs of auricular appendages 

 closely resembling internally as well as externally those of the foremost 

 joints (Fig. 1). The following measurements of scolex will be of use 

 for future diagnoses of species: — 



Width, at base of terminal disc . 20 — . 40 mm. 



Width, at posterior end of bothria 0. 17 — 0.25 mm. 



Width, at tips of appendages . 24 — . 38 mm. 



Length, including appendages 0.38 — 0.48 mm. 



A neck is absent, proglottidation beginning immediately behind the 

 scolex (Figs. 1, 5 and 6). Here the joints are short and crowded closely 

 together even in relaxed states of the strobila. The appendages are 

 united to form a sort of ring into which the narrow anterior end of the 

 next joint fits, leaving recesses between these two parts, which pass 

 forward a little farther laterally and dorsoventrally than at the ends of 

 the diagonal diameters (Fig. 35). In many preserved specimens these 



