December, '10] severins: dryness and walking-sticks 



TABLE 2 



481 



Transferred 



from dry to wet 



conditions 



Number of eggs hatched 



Specimens which had emerged completely 



from the egg-shell 



Specimens unable to emerge completely 

 from the egg-shell 



100 



80 

 20 



The table shows that 92% of the 100 specimens which hatched 

 from the eggs that were kept formerh' under wet conditions and then 

 transferred to dry, and 20% of the 100 specimens which hatched from 

 the eggs that were formerly kept under dry conditions, and then 

 transferred to wet, failed, after pushing off the operculum, to extri- 

 cate themselves completely from the egg-capsule. It is evident 

 from these experiments that dryness at the time of hatching has a 

 marked effect upon the emergence of the walking-stick from the egg. 



Bibliography 



1 Godeltnann, R., 1901. Beitrage zur Kenntnis von Bacillus rossii Fabr. mit be- 

 sonderer Berticksichtigung, cler bei ihm vorkommenden Autotomie und Regenera- 

 tion'einzelner Gliedmassen. Arch. Entwickmelk. XII, pp. 265-301. 



2 Heymons, R., 1897. Uber die Organisation und Entwickelung von Bacillus rossii 

 Fabr. Sitzb. d. Kgl. Akad. d. Wiss. BerHn XVI, pp. 363-374. 



3 Stockard, C. R, 1908. Habits, Reactions and Mating Instincts of the Walking- 

 stick, Aplopus mayeri. Publ. No. 103 Carnegie Inst., Washington, pp. 43-59. 



Coccidae of Boulder County, Colorado. — Mr. D. B. Thurston has recently 

 brought me two species new to the list, collected in Boulder this fall. These are 

 Aulacaspis rosce (Bouche),on cultivated Ruhus, and Pulvinaria innumerabilis (Rathv.) 

 on maple. The Pulvinaria has been known here for some years, but by some over- 

 sight I failed to obtain specimens before. From the Pulvinaria bigelovice on Chrys- 

 othamnus, already recorded, I bred a parasite, which has now been identified by 

 Doctor Howard as Coccophagus immaculatus Howard. In his Revision of the Aphe- 

 lininse Howard reports C. immaculatus only from Eriococcus azalece, in the District 

 of Columbia. It is rather surprising to find it now in the arid west, infesting a 

 coccid of a quite different group. T. D. A. Cockerell. 



