Got) 
P. zolicaon from Glenwood Springs, Colorado, and the latter 
species from British Columbia. He stated that there was a 
tolerably complete gradation from P. oreyonia (= machaon) 
through P. brucei to P. zolicaon, that none of the characters 
which had been relied on for separation were of real value, 
and that the structure of the genitalia afforded no assistance. 
Although P. bairdii appeared to be very distinct in appearance 
and habits, it was associated with the other forms in Colorado, 
and Mr. W. H. Edwards stated that he had bred both P. bairdii 
and I, oreyonia from eggs of the same female of either of the 
two forms. 
The working-out of the synonymy and specific differences 
(if any such existed) between the N. American Papilios of 
this group was one of the most difficult problems offered by 
the Butterflies, and one which was well deserving of an 
exhaustive study. 
Mr. J. J. Walker mentioned that he had bred P. zolicaon 
from larve found on Siwn, at Esquimault, Vancouver Is., 
and that neither larva nor pupa was distinguishable from 
that of P. machaon. 
Papers. 
Mr. O. H. Latter read a paper on “ The prothovacic gland 
of Dicranura vinula, and other notes,’’ in continuation of his 
previous communications on the subject. A fresh use of the 
formic acid secreted by the larva was described; it was 
employed to alter the silk secreted in spinning the cocoon, in 
order to convert it into the well-known horny mass. If the 
acid was prevented from acting, as by supplying the larvie 
with bits of blotting paper soaked in an alkali to be utilised 
in making the cocoon, the silk thus protected from the action 
of the acid retained its usual fibrous structure. 
Prof. Meldola spoke in appreciation of Mr. Latter’s work on 
this larva, which he characterised as being physiologically one 
of the most remarkable insects known. The most singular 
feature which Mr. Latter had discovered was its power of 
secreting free potassium hydrate, and it was of great import- 
ance to ascertain if possible the metabo'ic processes whereby 
this was effected. 
