SYNOPSIS OF NORTH AMERICAN BEES. 31 



could see that the malformed specimen was forming, and on 

 Nov. 15th it endeavoured to emerge, but, though the notch 

 behind the head did not seem to hinder the process of trans- 

 formation, yet the insect became a cripple from another cause, 

 the spiracle tissues apparently being too strong to release the 

 abdomen from its case. Perhaps this was due to excess of 

 moisture, or to a too quick development. 



From some other unknown cause the well-formed pupa died 

 about Nov. 30th, and I feared that my success with galii was to 

 be limited to a slight increase of experience, not the most happy. 



However, on Dec. 6th a specimen of C. porcellus emerged 

 satisfactorily, and to my great joy the third and last galii also 

 emerged satisfactorily on Dec. 19th, a perfect, though not very 

 large, male; the slight malformation of the antenna case ap- 

 parently having no detrimental effect to its contents. 



All my M. stellatarum have already emerged without forcing, 

 with the exception of the one experimented upon, which 

 succumbed under the unwonted treatment of heat and moisture. 



It will thus be seen that all have been subjected to the same 

 conditions with varying results of failure and success, and I 

 should much like to know why it is that one month's forcing 

 should affect one insect, while another should require twice that 

 period ; why, under the circumstances, one should live and 

 another die. Truly nature's ways, though full of interest, are 

 past finding out. 



Since writing the above, another perfect specimen of C. por- 

 cellus has emerged, — January 14th, — having required nearly 

 three months of this irregular system of forcing to complete its 

 transformation. 



107, Camden Street, Birkenhead : Dec. 22nd, 1897. 



SYNOPSIS OF THE NORTH AMERICAN BEES OF THE 

 GENUS NOMIA. 



By T. D. A. Cockerell, N. M. Agr. Exp. Sta. 



Mr. William J. Fox in 1893 (' Ent. News,' p. 134) gave a 

 synopsis of the North American species of Nomia, including, 

 however, only four species. One of these he described as new 

 under the name N. punctata, but this name being preoccupied in 

 the genus, Dalla Torre altered it to N. foxii. In the present 

 synopsis ten species are included. One other species' is known 

 from the western hemisphere — N. tarsalis, Westw., from Brazil. 

 The species of Eunomia, Cr. (not Eunomia, DC, a genus of 

 Cruciferse), viz. E. apacha, Cr., E. marginipennis, Cr., and E. 

 heteropoda, Say, are excluded. 



