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XVII. On the occurrence, near London, of the Flea Cera- 

 tophyllus vagabundus Boh. under unusual circum- 

 stances. By James Waterston, B.D., D.Sc, 

 F.Z.S., Assistant Keeper in the Department of 

 Entomology, British Museum (Nat. Hist.). 



(Published by permission of the Trustees of the 

 British Museum.) 



[Read June 7th, 1922.] 



Plate XXXV. 



Along with samples, which included both imagines and 

 larvae, of the coleopteron Xestohium ruforillosttm De 

 Geer (= tesselatum Ohv.), found to be dama^ging trusses 

 in the Great Hall, Hampton Court, several small rounded 

 objects were recently forwarded to the Department of 

 Entomology, British Museum. 



These have been studied by Dr. C. J. Gahan, Messrs. 

 M. A. C. Hinton, A. J. Willmott and myself, and our 

 unanimous opinion is that they are hawthorn {Crataegus 

 sp.) stones brought to the place of their discovery and there 

 devoured by mice. 



The cup-shaped appearance, to which attention is drawn 

 by the sender, Sir Frank Baines, H.M. Office of Works, 

 is due to the fact that one of the ends of the stone had 

 usually been bitten off by the mouse in getting at the 

 kernel. The truss, in fact, had been used as a Avinter 

 storehouse, and, besides the stones, yielded two shells of 

 the mollusc Candidula caperata Mntg. (det. G. C. Robson), 

 which may also have been brought in by mice. 



These hawthorn stones, brown and discoloured, especially 

 on the outside, must be of considerable age, though it is 

 impossible on the evidence available to say exactly how 

 old they are. On none of them is there any trace either 

 of the calyx of the flower or of the mealy pericarp. In 

 some the micropyle is large and obvious, and all are prob- 

 ably a trifle smaller than samples of stones prepared by 

 removing the pericarp mechanically. (In the latter case, 

 too, the micropyle is small and inconspicuous, and it is 

 only by excising some tissue that a passage to the seed 

 cavity can be demonstrated.) In one or two examples 



trans, ent, soc. lond. 1922. — parts hi, iv. (feb. '23) 



