THE CANADIAN ENTOMOLOGIST. 235 



In nature, the larva makes a cavity in the soil to transform in, press- 

 ing the soil firm and making the inside of the cavity as smooth as that 

 of a silken cocoon. So that the pupa lies perfectly free, which will 

 account for the fact that when placed in soil they always work themselves 

 to the surface. Freedom from irritating matter is then, I suspect, one of 

 the principal factors for successful maturing of them. And to those that 

 have passed the winter in natural conditions, moisture may be another, 

 but those that have begun their pupal existence in unnatural conditions 

 do not seem to feel the need of it. 



We know that it is comparatively an easy thing to get the pupa from 

 a sphinx larva, besides getting the imago from the pupa ; if, then, such 

 pupae can be matured without the labour and care required to get up and 

 maintain " natural conditions," with the probability of a disappointing 

 failure at the end of it all, what an inducement it would offer to many to 

 undertake the rearing of them who are now prevented from attempting it 

 by the elaborate preparations that seem required to ensure success. 

 Whilst, if safety and a soft bed is all that is required for success, many a 

 valuable chrysalid that is now rejected or neglected, under the impression 

 that it would be hopeless to attempt to rear it with the means they have 

 on hand, might be reared to add rare forms to a collection, or even to 

 aid in the identification of earlier stages of some of the species. An ex- 

 periment on an extensive scale in this direction is well worth the making. 



J. Alston Moffat. 



BOOK NOTICE. 



BRIEF GUIDE TO THE COMMONER BUTTERFLIES OF THE NORTHERN UNITED 



states and Canada : by S. H. Scudder. Henry Holt & Co., 

 i2mo., pp., XI + 206., 1893. 

 It has been known for some time that Mr. Scudder has in preparation 

 a Manual of the Butterflies of the Northern United States and Canada, 

 similar to Gray's Manual of Plants, and all must agree that such a work 

 is much needed. The present " Brief Guide " has, however, been pro- 

 duced in the meantime to meet a demand for something even less 

 technical, by means of which boys and girls might be tempted to enter 

 the ever charming fairy-land of science by having an easy way laid open 

 before them. There are few objects in nature which so soon thrust 



