Buchanan. — On Pseudo-scab and Lung-worm in Sheep. 269 



The only other species of Neritlna recorded from New Zealand is N. 

 zealandica, Eeclwz., P.Z.S., 1845, p. 120; but it appears doubtful if the 

 specimens were actually procured in this country. 



Those now under consideration were found among the debris brought 

 down by the Waikanae Eiver; probably if the stream were carefully 

 examined further up living examples might be procured, and it is important 

 that this should be done, in order that the animal may be described as well 

 as the shell. A considerable number of specimens were obtained, and sub- 

 mitted to careful examination, yet although there are minor points of 

 difference, the general characters agree so well with the description of N. 

 fitiviatilis that I am obHged to refer it to that species. Probably, however, the 

 animal when discovered will exhibit sufficient distinctive characteristics to 

 warrant the foundation of a new species. 



Art. XXXVIII. — On Pseudo-scab and Lung-worm in Sheep. 

 By John Buchanan, F.L.S. 



[Read before the Wellington Philosophical Society, 6th August, 1881.] 

 Pseudo-scab in sheep. 

 A DISEASE in sheep resembling Acari Scab, having recently attracted 

 attention among flock-owners, several pieces of affected skin were forwarded 

 by the Sheep Department to the Museum for examination and report, but 

 with no definite results, in consequence of the disease in every case having 

 reached its crisis and the wool having again begun to grow, and only in 

 one case was it clear that the skin had been burrowed by worms. 



The conclusions arrived at in lung-worm disease, regarding the life- 

 history of the lung-worm ( Strongijlus filar ia) , are clearly applicable in the 

 present case, and it is also highly probable that the same species or an 

 aUied one produces this eruption on the sheep, the eruption disappearing 

 in autumn, after which the sheep regain their usual health. The conditions 

 most favourable to the selection of the skin as a nidus, are wet seasons, 

 when the sheep are in a continually soaking condition from rain ; such 

 weather is also favourable to the movements of the young worms when in 

 search of a host. 



It is doubtful whether the worms in every case burrow into the skin, as 

 no doubt the clotted secretions of yolk at the base of the wool offer sufficient 

 shelter in many cases ; it is certain, however, that a scab is produced in 

 every case where the worms have selected the body as a nidus, and their 

 leaving in autumn is coincident with the departure of the lung-worm. 



