STRONGYLUS TETRACANTHUS. 



813 



Fig. 50. — Appearance of mucous membrane of colon of Iceland pony, natural size. 



I may state that all the jDonies affected were rising two years 

 old, and that several had died before my opinion was sought. 

 They had been imported from Iceland during the summer and 

 autumn of 1873, and thriven tolerably well until late in the 

 winter. They were at pasture during the whole winter and 

 spring, being allowed hay in addition to what they could graze. 

 There were many older animals amongst them, the lot being a 

 large one, all of which were quite free from the parasites. 



The question naturally arises, Are these parasites peculiar to 

 Iceland ? and at the first glance, my own experience would 

 compel me to answer in the affirmative ; but the observations 

 of others at once point to the conclusion that other than Icelandic 

 ponies are subject to the invasion, and Dr. Cobbold has arranged 

 the following list of those who have written upon the subject : — 



^^ Dick. — 'Worms at different stages of growth;' in MS. to Dr. 

 Knox, 1836. 



"Knox. — 'Animals similar to Trichina;' in Edin. Med. and Surg. 

 Journ. (loc. cit.) 



" Diesing. — ' IS'ematoideum equi cahalli ; ' Sgst. Helm., vol. ii. 1851. 



" Littler. — ' Extremely small ascarides ; ' in a letter to Mr Varnell ; 

 The Veterinarian, 1864, p. 202. 



"Varnell. — 'Entozoa in various stages of growth;' The Veteri- 

 nariari, ui supra, p. 265. 



" Williams. — * Entozoa from the intestinal walls;' in MS. to the 

 author, March 13, 1873. 



" Cohhold. — Trichonema arcuaia, a new species of nematode (with 

 description as below). 



