244 Zoology of Colorado 



It is figured in Ward's "Fresh Water Biology," p. 486. In the 

 same year another freshwater species, probably carnivorous, was 

 described as Tripyla lata, from Alpine Lakes, Bald Mountain. 

 Numerous other species will be found by any one who cares to 

 hunt for them. 



In addition to the nematoda, there are two other classes of 

 round worms, much less numerous in species. The Gordiacea 

 or hair-worms, parasitic in insects, are very degenerate creatures, 

 the mouth absent and the intestine not functional in adults. 

 The eggs are laid in water, and the young on hatching bore into 

 the tissues of aquatic insect larvae, such as those of May-flies. 

 Well grown hair-worms occur in the body cavity of terrestrial 

 insects, such as crickets; but eventually the adult worm lives a 

 free life in water, becoming sexually mature and producing a cord 

 of eggs which may be several feet long. Full particulars of the 

 species are given in Ward's book already cited. These hair- 

 worms are common in Colorado, and here, as elsewhere, the 

 legend is current that they arise from horse-hairs. The species 

 we have found at Boulder has not been identified, but it is prob- 

 ably Paragordius varius of Leidy, which is known to exist in 

 Kansas, Nebraska and California. The tail end of P. varius is 

 trilobed in the female and bilobed in the male. 



There is another peculiar group called Acanthocephala, the 

 name meaning spiny-head. They have a spiny proboscis, with 

 retractile hooks, by which they attach themselves to the intestines 

 of their vertebrate hosts. There is no alimentary canal in any 

 stage of development. Hall records Echinorhynchus in the in- 

 testines of the domestic pig in Colorado. According to Kaupp 

 it was said to be common at Fort Collins. 



ROTIFERA 



The rotifers or wheel-animalcules are microscopic, living 

 abundantly in fresh water. They look at first sight more like 

 Protozoa than worms, but as they are more or less transparent 

 it is possible to see their complicated anatomy while they are 

 still alive. No careful study of the Colorado species has been 

 made, and only a few have been recorded.* A fine red species of 



♦University of Colorado Studies, vol. VIII (191 1) p. 248. 



