EtONOMIC IMPORTANCE OF NEMATODES. 325 



II.— Nematodes in Domesticated Animals. 



All genera of vertebrates are said to liarbour one or more 

 species of Nematode parasites. Often, however, the number of 

 parasites that are peculiar to certain hosts, such as sheep, oxen, 

 horses and dogs, is quite formidable, and the losses incurred 

 as a result of their activities are very considerable. 



The study of the Nematode parasites of domesticated 

 animals, their life-histories and methods of control, has already 

 attained considerable proportions, as shown by the literature, 

 but much still remains to be done. The taxonomy is difficult. 

 Only a rough classification, sufficient to indicate the general 

 position of some of the principal parasites, is used here. 



The following is a list of some of the chief Nematodes 

 found in domesticated animals : — 



ANGIOSTOMIDAE. 



Strongjjloides papillosus (lotujus) is parasitic in 

 the small intestine of sheep, pigs and rabbits. 



PiohsUiunjria vivipara is found in the large intes- 

 tine of the horse and donkey. 



GNATHOSTOMIDAE. 



Gnathostoma Jiispiduin is found in the stomach of 

 the pig and ox. 



FILARIIDAE. 



Filar ta initans is the cause of " summer sores " 

 in horses in Australia. 



F. clava occurs in the peri-tracheal connective tissue 

 of the pigeon. 



F. spiculaiia occurs in the sub-pleural and sub- 

 peritoneal tissue of the ostrich. 



F . gaUinarinn occurs in the intestine of the fowl. 



F . (Diio florid ) immitis is found in tlie heart of 

 dogs. 



F. (Setaria) equina occurs in the jieritoneal cavity 

 of horses. 



Thelazia — T . lacrymalis and other species are para- 

 sitic in the lachrymal glands, eyeball and under eyelids 

 in many mammals, e.g., horse, ox, buffalo, camel, dog. 

 A vspecies was recently found in the eye of an ox in 

 Johannesburg. 



Onchocerca reticulata has been found in the 

 ligaments of the fore-limbs of horses; 0. cervicalis in 

 liorses ; 0. lienalis in cattle, and 0. gihsoni occurs in the 

 subcutaneous (" wormy ") nodules in cattle in Queens- 

 land. 

 Besides being the host of the adult worms, many larval 

 Nematodes (Microfilariae) are found in the blood of cattle in 

 India and Africa. 



Spiroptera megastoma and ;S'. microstoma occur in 

 the stomach of the horse and donkey ; >S'. sanguinolenta 

 in the dog; ,S'. pectinifera in gizzard of fowl; 

 ,S^. strongylina in stomach of pig. 



