New British Orihatidm. By A. D. Michael. 387 



taking over six months, during which they had to be 

 looked to almost every day, until at last they were full grown and 

 became the remnrkable creatures I have described. I then killed 

 and preserved two for specimens, retaining the other two alive so 

 as actually to complete the whole cycle of changes. Unfortunately, 

 when one of these was just about to assume the adult condition, by 

 a trifling accident something touched my hand while I was ex- 

 amining the cell, and the creature which I had kept for six months 

 was gone in an instant. I, however, still had one left, and this one 

 I was more fortunate with, and succeeded in rearing it through the 

 final ecdysis ; it completed the whole cycle of its existence in 

 my cage and became a perfect CepJieus hijiclatus on the oOth April, 

 1885.* I retain it as a specimen with the cast skin from which it 

 emerged. 



Another very interesting new species is that referred to below as 

 Hy2oocthonius lanatus. The genus Hypocthoniits was instituted 

 by C, L. Koch for two species which he described. Nicolet finding 

 that Koch had established several genera upon immature forms, 

 and seeing that this looked very much like a nymph, positively 

 stated that this genus also consisted of creatures in course of 

 development, and even went so far as to say what it was the early 

 stage of. Dr. Gr. Haller, some few years since, pointed out that 

 Koch was right and Nicolet in error, as the sexes are well developed 

 and the female is constantly found with ripe eggs. From careful 

 observation of the different species both living and in preparations, 

 I can fully confirm Haller's view ; the female lays ripe and fertile 

 eggs in the ordinary way, and neither she nor the male ever 

 undergo any further transformation, while, as I have formerly 

 stated, I have traced the larva and nymph of the species which 

 Nicolet supposed this to be the immature stage of, and they are 

 totally different. The great point of interest, however, is the 

 following. In almost all general works on zoology the A carina 

 will be found described in words practically of similar purport to 

 the following, which is taken from the English translation of 

 Cohn's Text-book of Zoology (1884). " Acarina, Arachnida with 

 stout body. The abdomen is unsegmented and fused with the 

 thorax ; " and further on, " The body of the Acarina is generally 

 small and possesses a stout and unsegmented form. The head, 

 thorax, and abdomen are fused into a common mass." Now this is 

 perfectly true of such extreme forms as the Hydrachnidae, but in 

 the Oribatidse, most of the Gamasidse, the Trombidiidae, the 

 Tyroglyphidse, and indeed far the larger part of the Acarina, the 

 abdomen is as distinct from the cephalothorax as that of a beetle is 

 from its thorax. In this genus, however, the matter is carried 



* The imago had not emerged at the time this paper was read, but has done 

 60 since. 



2 c 2 



