The Life-history of an Acariis, d'c. By A. D. Michael. 379 



hypopial nymph closely resembled Lahidophorus talpse, almost 

 the only differences being size, and that the hind tarsi of Haller's 

 species terminated in very long single spines, whereas Kramer's 

 terminated in a I.1 ach of short, fine hairs. Haller found his Acarus 

 in great numbers and in all stages on the squirrel, and called the 

 adult Dermacarus sciurinus, and he gives an exhaustive description 

 and illustration of his creature at all ages in his paper.* The 

 hypopial nymph, however, was not first discovered by Haller ; it 

 had been figured and described, somewhat imperfectly, long before 

 by C. L. Koch,t a fact which Haller is careful to point out, Koch 

 had treated it as a separate species, and classed it among the 

 Dermaleichi ; it was Haller who traced its life-history, and assigned 

 to it its proper place. 



During some investigations which I made into the life-histories 

 of Pygmephorus spinosus, Kramer's other mole-parasite, I very 

 frequently met with his Lahidop)horus talpse ; I felt that this must 

 probably be a hypopial nymph, and that it would be very in- 

 teresting to trace its life-history ; but, less fortunate than Haller 

 with his squirrel-parasite, I was not even able to find on the mole 

 any Acarus which was at all likely to be the adult form ; and, 

 indeed, except the species I was investigating, I could not find on 

 it any Aea^'us, the whole life-history of which was not well known 

 to me. I tried, therefore, to rear the Hypopus in confinement and 

 observe what adult form it changed into. I was not, however, 

 as successful in this as I have been in similar efforts with other 

 species ; I could not get the Hypopus to live away from the mole, 

 and of course I could not keep the mole under observation. For 

 some years I have, from time to time, continued this inquiry ; 

 catching moles when I had the chance, and usually obtaining the 

 Hypopus ; but still failing to rear it. 



As I was spending the Christmas of 1885 in one of our 

 Midland counties, I again utilized the occasion to pursue the 

 subject. I caught twelve moles, and obtained plenty of Labido- 

 phorus, but there the matter ended. I was still unable to discover 

 any conditions which would enable me to keep them in health away 

 from the mole. At last it struck me that if I obtained and searched 

 the mole's nest instead of the moles themselves, I might possibly 

 find the creature in the adult stage, or in some stage which would 

 be easier to rear than the Hypopus. I therefore proceeded to dig 

 up moles' nests, and obtained about a dozen. I was careful to 

 mark those which, from external appearances, I thought were fresh 

 nests ; in these nests I found several species of Asiari, and among 



* " Zur Kenntniss der Tyroglyphen und Verwandten," Zeitschr. f. Wiss. 

 Zool., xxxiv. (1879) pp. 261-73. 



t ' Deutsclilands Crustaceen, Miriapoden, und Arachniden,' Regensburg, 

 1834- 9, Heft 33, fig. 7. 



2 c 2 



