HOUGHTONj ON THE MANGOLD-AVURZEL PLY. 39 



iuvesting membrane that there is no direct connexion between 

 this organ and the oral sucker. Its excretory duct lies in 

 front of the ovary. In all Gyrodactyli^ wherCj generally 

 speaking, a single egg with its yellow shell came under obser- 

 vation, there Avas only this solitary example seen, and its 

 escape was but once observed. The two seminal vesicles 

 standing out most conspicuously in Gyrodactylus tenuis, are 

 filled hy a convolution of filaments, and intercommunicate 

 by a canal. The connexion of the posterior seminal vesicle 

 with the presumed testes was not perceivable ; the anterior 

 one is connected Avith the external, horny, male-reproductive 

 apparatus. The latter organ is characterised by a great 

 variety of form, so that one may say ' Ex pene speciem.' 

 Speaking generally, we observe a peculiar, more or less 

 curved penis, grooved for the passage of the semen, and an 

 accessory solid portion Avhich is often hooked ; the latter 

 serving, probably, as a fang or organ for adhering to the 

 vagina. In one instance, where the accessory portion was 

 absent, two booklets at the entrance of the vagina in all 

 probability represented the same, for the pui^iose of laying 

 hold of the penis when lodged within the sheath. Thus 

 Gyrodactylus sometimes becomes sexually developed, and 

 cannot be regarded merely as a form of ' Nurse.' " 



OBSERVATio>is OH the Fly affecting the Mangold Wurzel 

 Crops, in the year 1861. By the Eev. W. Houghton, 

 M.A., F.L.S. 



The mangold wurzel crops have, as is too well known 

 amongst farmers in some parts of this country, suffered con- 

 siderably from the attacks of the larvte of some insect during 

 the last year. In the report of the meeting of the Entomo- 

 logical Society, July 1, 1861, Professor Westwood observed 

 " that although mangold wurzel has been usually considered 

 almost free from the attack of insects, yet the crops this 

 season in many distant countries, Devon, York, Hereford, 

 Gxon, &c., were attacked by the larvae of a dipterous insect, 

 Fam. Muscidce, and probably allied to Tephritis, which mine 

 into the leaves, forming large blotches, which soon shrivel up 

 and do much damage to the plants.'^ In the Journal of the 

 Royal Agi'icultural Society of England, vol. vii, p. 399 (1847), 

 Mr. Curtis has published some ' Observations on the Nat. 

 Hist, and Economy of a Weevil aflecting Pea-crops, and 

 various insects which injure or destroy the Mangold AYurzel 



