342 [August, 



The nymph (Fig. B) is very similar to the imago ; it differs only 

 in the shorter wings, and in the first abdominal segment being a little 

 stouter. 



The cases (Fig. E) of the host, when agriotypized, bear on their 

 head end a long band-like appendage, spun of the secretions of the 

 salivary glands. It is of a dark brown colour, and much exceeds the 

 case itself in length, being, in Silo pallipes, 17 mm., and in Silo 

 nigricornis, 26 mm. long and 1 mm. broad. 



■ Von Siebold suggests that the larva of Silo, when infested, spins 

 this appendage, and we find this opinion in all more recent books. It 

 seemed somewhat curious to me that the larva, being 

 exhausted by the parasite, should have such an 

 amount of the material for spinning, and therefore 

 I have examiner! a large number of agriotypized 

 cases, and found the relations as they are indicated 

 in the Fig. G. On each of the examined cases I 

 found the normal covers of Silo ; a thin membrane 

 anteriorly (v 1), to which is attached the stone which 

 closes the mouth opening of the case, and posteriorly 

 a strong membrane (w 1), furnished with the usual 

 little holes. The larva or nymph of the parasite rests 

 in a sort of cocoon (v 2 and w 2), whose sides are 

 very closely connected with the sides of the case, 

 and which leaves empty a little space of 1-| mm. in the hind part of 

 the case. To the anterior part of it is attached the appendage, which 

 has been spun separately, and with its widened basis connected with 

 the cocoon spun afterwards. The appendage penetrates through the 

 membrane made by the larva of Silo, and arises between the wall of 

 the case and the stone closing the mouth opening of the case. The 

 chitinous remains of the larva of the host (s) lie in the empty hind 

 part of the Cc.se. In cocoons enclosing the larva? or subnymphs of 

 the parasite there was resting on their posterior cover a ring of excre- 

 ment (k), and in those enclosing a nymph (ag) also the cast skin of 

 the larva (e). I believe then that the parasite allows the host-larva 

 to prepare everything for changing into a nymph, to attach the case 

 to stones and to close it, then devours it and forces the remains into 

 the hind part of the case, makes the appendage, and finally spins the 

 cocoon, in which it changes to the subnymph and afterwards into the 

 nymph. 



With respect to the period of the whole life of Agriotypus aronahis, 

 I will enumerate here all my observations, and the localities in which 

 I have founcVit, arranged according to the time of year. 



