Hardwicke's science-gossip : an illustrated medium of interchange and gossip for students and lovers of nature . 163, 164. Cases of Halesus digitatus. It now remains to me to speak briefly of a pecu-liar instance of form belonging to extra-Britishspecies. In the streams of Southern ContinentalEurope, and of various other parts of the world, areto be found little cases formed in shape of a smallsnail-shell. These are termed Helicopsyclie, and haveonly recently been proved to be the work of Caddis-worms, they having been repeatedly described asthe shells of Mollusca, under various name
Hardwicke's science-gossip : an illustrated medium of interchange and gossip for students and lovers of nature . 163, 164. Cases of Halesus digitatus. It now remains to me to speak briefly of a pecu-liar instance of form belonging to extra-Britishspecies. In the streams of Southern ContinentalEurope, and of various other parts of the world, areto be found little cases formed in shape of a smallsnail-shell. These are termed Helicopsyclie, and haveonly recently been proved to be the work of Caddis-worms, they having been repeatedly described asthe shells of Mollusca, under various names. Caddis-worms have six legs, attached to the three thoracicsegments, which, with the head, are of a horny tex-ture above, these forming that portion of the bodyprotruded when the creature is feeding ; the abdo-men is soft, the first segment usually carrying threehumps, one median, and one on each side, whichserve, with the assistance of the hooks at theextremity, to prevent the larva being dragged fromits case ; so that it is often impossible to ejectwithout introducing a twig into the tail-end andpushing
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