STEONGYLID^ OK PALISADE-WOEMS. 



71 



carried out in the dung. The embryos are seen to develop in 

 damp mud and in water, and are thus taken by the horse. 

 The female is often as big again as the line representing the 

 natural size in the figure. Another form, the Giant Palisade- 

 worm {S. gtgas), is a red worm nearly a foot in length in the 

 female, and lives in the pelvis of the kidney in both horse 



Fig. 23. — Armed Palisade-worm of Horse (Sclerostoinum arinatum). Female. 

 a, Male bursa. (Line nat. size.) 



and man. Sometimes severe epizootics of these Palisade-worms 

 break out. 



Sderostomuvi ietracanthum (fig. 25) and 8. ruhrum (fig. 26) 

 are usually the most injurious Strongyles in the horse. The 

 former is a pinkish- or brownish-white worm, varying from 

 8 mm. to 16 mm. in length, the male being smaller than the 

 female, and provided with a bursa excised on the ventral sur- 

 face, the female having a pointed tail. On each side of the 

 body, a little in front of the end of the oesophagus, is a long, 

 lateral, spine-like body. 8. rubi'um is very similar, but is 

 always red in colour and smaller in size, and has no lateral 

 spines. These two Solerostomes have a similar life -history. 



