2l6 CHILD. [VOL. I. 



Some of the figures show the dorsal side uppermost, others 

 the ventral. The position is noted in most cases. In each 

 figure the furrows of the lower side are drawn as broken lines. 

 In cases where they gradually become shallower and disappear 

 upon the surface of the proglottid, as they often do, the attempt 

 is made to represent the general character of the line by a lighter 

 or finer line in the figure on the upper side, and on the lower by 

 longer spaces between the dashes composing the broken line. 

 In the figures of abnormalities the testes are not represented. 

 Nearly all figures show stages before the uterus appears. 



The reproductive organs are represented schematically, for 

 the exact details of structure are not essential to the object of 

 this paper ; but the position and relation of the organs is shown 

 as exactly as possible. 



Since it will be necessary to employ various terms with refer- 

 ence to the segments in the course of the description and dis- 

 cussion of the figures, it seems advisable, in order to avoid any 

 possible confusion, to explain briefly the nomenclature employed. 

 The terms "proglottid " and "segment " are used as synonyms ; 

 "anterior" and "posterior" possess of course the same signifi- 

 cance as when applied to the whole animal; "transverse" is 

 applied as referring to the direction perpendicular to the longi- 

 tudinal axis of the animal, and parallel to the two flat surfaces, 

 the ventral and dorsal; the "width" of a segment is equal to 

 its transverse diameter; the term "longitudinal" refers to the 

 direction parallel to the longitudinal axis of the animal and the 

 "length" of a proglottid is equal to its longitudinal diameter. 

 In the form under consideration the width of a proglottid is 

 much greater than its length. The "thickness" of a segment 

 is its dorso- ventral diameter. "Right" and "left" are used 

 with reference to particular figures and do not always refer to 

 right and left sides of the body. " Side " is used as referring 

 to the region of the proglottid indicated by the preceding adjec- 

 tive, e.g., "dorsal side," "right side," etc. The " inter-proglot- 

 tidal furrow," " inter-segmental furrow" or "furrow' is the 

 furrow or line which separates the proglottids. A "partial 

 proglottid " is a portion of a proglottid incompletely or com- 

 pletely marked off by furrows. "Partial division " refers to the 



