294: Mr. H. A. Biiylis on soms 



Thickness — at end of oesophagus 009 0"09 



„ at middle of body 0-10 0-U 



„ at anus 008 0-07 



Leugthof oesophagus (including buccal cavitv). 0*o3 0"60 



tail '. . 0-19 0-22 



„ spicules 007 .... 



Distance, head to end of buccal cavity 0"125 0125 



„ „ nerve-ring 0"2G 0"31 



„ „ vulva 1'9 



a 34-7 30-9 



^ 6-54 5-78 



y 18-26 15-77 



This form agrees well in essential points with the type- 

 species, D. inarioni, de Man (1888). It is, however, sligiitly 

 larger, and differs in certain other respects. The body is ot" 

 very even thickness throughout the greater part of its length. 

 Towards the head it tapers rather rapidly, and the posterior end 

 begins to diminish in diameter from a little distance in front 

 of the anus. The tail (tig. 4, p. 296), in both sexes, tapers 

 rapidly for about the first half of its length ; more posteriorly 

 it becomes cylindrical, and, finally, near the tip there is a 

 slight swelling. The tip of the tail is bluntly rounded, and 

 the aperture of the caudal glands is not conspicuous. These 

 glands, however, are well developed (tig. 4, C.G.). 



The cuticle is quite smooth, as in the type-species, no 

 transverse striations beinor visible. No hairs occur on the 

 body, with the exception of four short, stout, submedian 

 bristles situated close to the anterior end (tig. 3, S.). The 

 lateral fields have a width of 0*025 mm. No lateral organs 

 have been made out. In the type-species of this genus they 

 are said to be present in the form of grooves {^^ sillons"), but 

 notliing of this kind has been detected in the present form. 



The mouth (tig. 3) is a small funnel-shaped depression and 

 is not provided with distinct lips. It leads into a small 

 *' vestibule," as in U. marionij at the base of which there are 

 three teeth (fig. 3, 2'.) arranged in a triangle, andleach shaped 

 somewhat like a boot-tree. This vestibule is followed by 

 the buccal cavity pro]jer (fig. 3, Ph.), consisting of a greatly 

 elongate, rigid, chitinous tube. This decreases gradually in 

 diameter from before backwards, its walls, comparatively 

 thick in front, becoming also gradually thinner towards the 

 posterior end. The distance from the mouth to the posterior 

 end of this tubular buccal cavity is about a quarter of that 

 from the mouth to the hinder end of the oesophagus. The 



