Dermatoxys hispaniensis n.sp., collected from the intestine of hares and wild rabbits is described, and details are given of the cephalic anatomy. As far as our knowledge goes, this is the first record of Dermatoxys in Spain and also in the leporine species of Europe.

A key for identifying the species of Dermatoxys is provided, based on the available data.

A study has been made of the early larval stages of the nematode Trichuris muris. It was found that the capacity of larvae to infect mice developed some time after the apparent completion of growth in the egg; no moult was observed to occur within the egg. Hatching took place in the small intestine of the mouse between 30 and 60 minutes after infection and the larvae were carried down into the caecum. Penetration was first observed one hour after infection and by 4 hours almost all the larvae had entered the caecal mucosa. Larvae appeared to penetrate into the epithelial cells of the mucosal glands after first entering through the gland opening. During the first 4 to 5 days the larvae remained within the glands, coiled around the gland lumen, but as growth occurred, the larvae occupied a more superficial position and eventually came to lie with the anterior region of the body within the mucosa and the posterior region lying free in the caecal lumen. Moulting larvae were recovered on the 9th 10th and 11th day after infection.

Page 159. For ‘N. triserialis’ for ‘N. imbricatus’ in legend to Fig. 14.