12 ENTOMOLOGICAL SOCIETY 
that the extraordinary resemblance between these two insects of 
two quite different families must be a purely accidental one, 
having no connection whatever with mimicry. 
Dr. Barnard exhibited a specimen of Harpalus pensylvanicus 
infested by a Hair-worm, and remarked upon the structural char- 
acters, the development and habits of Gordius and Mermis. 
He also mentioned the fact that Mermis acuminata has been 
found in the Apple-worm (larva of Carpocapsa pomonella} , and 
in explanation of this fact he proposed the theory that immature 
larviE from fallen fruit returning to the tree get attacked while 
thus on the ground, and ascend to enter other fruit thereafter on the 
tree, and that this will account for the cases observed. 
Mr. Marx read a paper on the geographical distribution of 
Arachnida in North America, going through the natural families of 
the Order, and dwelling upon the peculiarities exhibited by each 
family in connection with the geographical range. 
Mr. Marx offered some remarks on the mode of respiration in 
Epeira sylvatica as observed in a living specimen which he had 
received from Ft. Stevenson, Dakota. The pneumatic stigmata 
were found to open and close alternately at regular intervals, 
whereas the hitherto accepted theory was that the stigmata lead- 
ing to the lungs were constantly open and prevented from being 
closed by the horny ring, or bulla, surrounding the aperture. 
Mr. Marx read some biological notes on Latrodectus mactans, 
especially on its mode of capturing insects by means of a sticky 
fluid exuded from the spinnerets. The variability in general 
appearance, coloration and markings exhibited in this species in 
its different molts is really wonderful, and the following specific 
names must be considered as synonyms: L. perjidus Walk., 
variolus ^Nz\k., formidabilis Walk, and intersector Fabr. 
Mr. Howard stated that the collection of Lepidoptera of Mr. 
Mead had been purchased by the Rev. Mr. Holland, of Pittsburg, 
Pa. 
OCTOBER 2, 1884. 
Six members present. Vice-President Marx in the chair. 
Lieutenant Casey remarked upon, and illustrated by drawing, 
a monstrosity observed in a Longicorn beetle of the genus 
