REPTILIAN TAPEWORMS. 251 



helones *. For in that Bothrioceplialid the uterine pore or genital 

 pore opens into one oi- other of the grooves. In fSolenotceoda, on 

 the other hand, the groove is actually the interior of the median 

 stem of the uterus, which is exposed to the exterior by a splitting 

 of the integument. The origin of this state of aiiairs is a question 

 to which I shall recur later. The extent and depth of the groove 

 is indicated in text-fig. 48, when seen from below in a pi-oglottid 

 mounted entire, and in text-fig. 49 in transverse section. On 

 the superficial view the actual groove is seen to occupy as nearly 

 as possible the median venti'al line of the pi'oglottid, and to be not 

 broader than l/7th to 1/lOth of the diameter of the proglottid. 

 The variation in breadth is of course due to the amount of gape 

 of the slit, which may be quite coextensive with the breadth of the 

 median stem of the uterus. 



In transverse sections (see text-fig. 49) the gape of the ventral 

 groove is often seen to be fully as wide as the lumen of the 

 uterus. The diverticula open into this canal on either side. On 

 the whole they form two more or less regular rows, one on each 

 side (right and left) of the median groove. I have, however, seen 

 them more crowded, two diverticula opening close together on one 

 side and one on the other. There is thus no perfect regularity, 

 as is indeed generally the case with the uterine diverticula in 

 the Ichthyota3niids. 



It is very noteworthy that the continuous slit later nowhere 

 shows signs of tearing or bursting ; its edges are smooth and 

 regular. This, of course, might be explained by the pre-existence 

 in earlier stages of the development of the uterus of a series of 

 uterine pores, increasing slightly in longitudinal diameter, and 

 thus leading eventually to a smooth and easy tear, such as is 

 effected in sheets of postage stamps. To this matter I shall 

 again draw attention in considering immature stages of the 

 viterus. I have examined carefully the end of the ventral 

 groove, close to the ovary, where the uterus of course 

 commences. 



The conditions met with at this end of the uterus are very 

 suggestive of a pre-existing pore. There is, in fact, as shown in 

 the accompanying drawing (text-fig. 50, p. 252), a distinct and 

 funnel-like in-pushing of the subcuticular layer of cells (and over- 

 lying cuticle), which opens into the cavity of the median stem of 

 the uterus. The subcuticvdar cells in the funnel-like in-pushing 

 come to lie at right angles, or nearly so, to the subcuticular cells 

 upon the general surface of the body. The narrow aperture of 

 communication thus formed, widens out in subsequent sections 

 to the wide gape already described. It must be admitted that 

 this funnel-like involution (as it apparently is) is not altogether 

 like the uterine pores which I have recently described and figured 



* Loinibevg, " Anatomische Studien iiber skandhiavische Cestodeii," K. Svensk. 

 Vut.-Ak. Handl.Bd. xxiv. (1891) No. 6; for a figure, see Bromi's Tliieneich.'. lid. iv. 

 Abth. IB, Taf. xlvi, fig. 4. 



17* 



