boU DR. F. E. BEDDARD ON 



The large size of the scolex of Dasyiorotcenia contrasts with the 

 relatively small or even minute scolex of other Tetracotylea, and 

 thus recalls that of the Tetraphyllidea and others of the "lower" 

 groups of Tapeworms. So also do certain other characters of 

 the scolex in this worm. The greatest diameter of the scolex is 

 3 "5 mm., and it is of much the same length, so that its dimen- 

 sions are but little less than the diameter and thickness of the 

 body, and are greater than those of the neck-region which imme- 

 diately ensues. Broadly speaking, the scolex is of a globular form 

 and has a soft, easily inden table, irregular surface marked by faint 

 ridges and depressions, and not at all like the vertex of a typical 

 member of the Tetracotylea. Two flat plate-like areas are to be 

 seen when the scolex is examined in this way with a. pocket-lens. 

 These are, as I believe, the expanded suckers which I have seen 

 in a contracted condition in another specimen whose scolex was 

 studied by means of transverse sections. 



Transverse sections of the scolex (text-fig. 94, p. 679) are 

 approximately circular in oi:itline, in the middle part at any rate. 

 This particular scolex, which I stvidied by the section method, 

 was apparently more retracted than the one represented in text- 

 fig. 93. For at first the sections (text-fig. 95) showed two semi- 

 circular masses closely applied along the straight margin which 

 is obviously the expression of an apical groove in the scolex. 

 It was lower in the series than this that the contour of the 

 sections became circular. At the body end of the scolex the 

 latter slightly overlaps the neck for the whole of its circum- 

 ference. But although the sections through the scolex are on the 

 whole circular in form, the pei-ipheral layer is not at all uniform 

 and shows numerous processes and grooves occurring everywhere, 

 which is an expression of the irregular grooving and ridging of 

 the scolex apparent when that region is examined with a hand- 

 lens. I could detect no symmetrical arrangement in these pro- 

 jections and grooves, which, however, may collectively represent 

 "bothria" meandering over the surface of the scolex. 



It is furthermore the fact that these grooves are converted in 

 places into tubes which run along the interior of the peripheral 

 layer of the scolex in a longitudinal direction, though not for a 

 long distance. These short tubes end blindly. Their existence, 

 together with the grooves and ridges of which they are a further 

 development, must facilitate the adhesion of the scolex to the 

 surrounding walls of the cyst. While the more or less irregular 

 grooves and furrows upon the svirface of the scolex might be put 

 down to irregular contraction of its outer layer, this can hardly 

 be the case — one would suppose — with these invaginated tubes. 

 In any case the arrangement of the suckers does not conform to 

 the arrangement usually met with among the Teti^acotylea (to 

 which group this worm would be expected to belong). The scolex, 

 however, possesses four suckers which are of very small size when 

 compared with the diameter and circumference of the scolex. 



