A. W. Rymer lioBEiiTs 307 



lengtli between A. obfictirufi and A. sjjulator at the same age. Now 

 the larva of A. sputator is full-fed when of a length of 16-17 mm. and 

 assuming that its rate of growth is the same as that of obscurus it should 

 attain this size by the end of its third year of life. Allowing then for the 

 period at the end of the larval stage, during which but little increase in 

 length takes place, it may be concluded that pupation occurs during the 

 fourth year and that the mature beetle emerges four years after the 

 hatching of the egg, or one year less than the time taken in the life cycle 

 by A. obscurus. We have as yet little accurate information as to the 

 duration of the life cycle in other species of the genus, but Xambeu 

 states(i2) that A. sordidus occupies only one year in the larval stage, 

 while Hyslop found(6) that A. mancus, an American species, in the 

 northern United States of America, pupated after three years. It seems 

 probable, therefore, that the duration of the life cycle varies much 

 between different species of the genus and the evidence so far is in favour 

 of A. sjjutator accomplishing it in one year less than A. obscurus. 



Other points in the life history coincide closely with those of A. 

 obscurus, though there may be differences not yet observed. The larvae 

 of both moult twice in the year, they pupate at the same time and the 

 beetle emerges from the pupal condition also at the same time. Kollar 

 says that the duration of the pupal stage is only fourteen days. This 

 has not been verified and may perhaps not apply to the climatic con- 

 ditions of this country. 



No difference in regard to choice of soil has been observed, though 

 A. sputator appears to require milder conditions, being comparatively 

 scarce north of Cheshire and Norfolk and rare in Scotland, while it is 

 not known in Ireland. On the continent of Europe also, though its range 

 generally coincides with that of A. obscurus, it becomes rather scarce in 

 the centre of Sweden (Thomson) and in Finland (du Buysson), while 

 A. obscurus occurs as far north as Lapland. 



In regard to the morphology of the larva certain external features, 

 specified in detail later on, have emerged from comparison between the 

 two species, differentiating them from one another. In the first instar, 

 at least, the characters of this species separate it also from A. acu- 

 minatus, Steph. {sobrinus, Kies.). It has not yet been possible to com- 

 pare it with^. lineatus, L. and .4. paUidulus, 111. The first-named must, 

 however, from Beling's description, closely resemble A. obscurus, while 

 A. paUidulus according to the same author seems to lack the sensory 

 pits on the 9th abdominal segment and to resemble rather the larva of 

 Dolopius marginatus. 



20—2 



