Two New Strepsipterous Insects. 51 



summer, were in reality those of the true Xenos found upon 

 Polistes or those of Stylops ; some being also mentioned which, 

 completing their final metamorphosis within the space of a few 

 weeks, did not assume the imago state until towards the end of 

 summer (31st result) ; thus coinciding with the period when Rossi 

 was accustomed to meet with the pupae of Xenos, namely, during 

 the months of August and September.* 



It is therefore to be regretted that, by collectively embodying 

 under one category results derived from the Stylops Melittce, 

 Xenos Rossii and Xenos? Sphecidarum, and by simply setting forth 

 the deductions so obtained, Dr. Siebold has afforded us no oppor- 

 tunity of classifying the evidence for the purpose of comparison, 

 whereby its bearing upon other points might be correctly ascer- 

 tained, and a consistent series of well -assorted facts more accu- 

 rately propounded. 



Much still remains to be ascertained in connection with the 

 history of these parasites ; no satisfactory explanation having yet 

 been afforded of the phases which more immediately precede, 

 accompany, and follow, the ingress of the hexapod progeny into 

 the bodies of the Hymenopterous larvae ; of the instincts displayed 

 to this effect by the former, the preliminary development acquired 

 by the latter, or the conditions (of abstinence or otherwise) im- 

 posed upon the parasites during the interim ; nor indeed, after so 

 locating themselves, does it appear unequivocally demonstrated by 

 what process they then pass from the hexapod to the apodal form, 

 unless indeed it should be understood that Dr. Siebold actually 

 verified the casting of the larva skin, (alluded to under his 8th 

 result,) followed perhaps by that atrophy of the organs of loco- 

 motion and plethoric distension of other parts, noticed by Mr. 

 Newport in the larva of Meloe, although he is disposed to believe 

 that the latter " does not enter the body of the bee-larva ; that 

 in all probability it wounds it, and preys on its fluids from with- 

 out ; . . . . and either that, having destroyed the recently hatched 

 bee-larva, its first tegument is cast, its mandibles are altered, and 

 it then subsists on the food that had been stored up for the bee in 

 the closed cell, and there gradually changes its form ; .... or 

 that, like the larva of Clerus, having destroyed the bee in one 

 cell, it penetrates into another and preys on the inhabitant until it 

 has attained its full growth, when it remains in one of these cells 

 and undergoes its metamorphoses;" various circumstances recited, 

 leading him " to incline to the first of these views." "j- 



* Fauna Etrusca, Mantissa, App. No. 97, p. 115. 

 t Trans. Linn. Soc. vol. xx. p. 354. 

 E 2 



