289 
alcohol for at least three years, so that the exact histological struct- 
ure of the nuclei could not be clearly brought out, but in the gen- 
eral appearance of these grandular cells, there is a general and 
suggestive resemblance to those filling the pleuropodia, figured 
and described by Wm. M. Wheeler.* At BZ is represented 
a section on one side of the middle, but still showing the 
spacious lumen. In the section represented by C the knife passed 
through the process still nearer the outer edge and near the 
base ; at C' three of the glandular cells with their large deeply 
stained nuclei are drawn. A transverse section at D shows the 
large lumen or cavity (/) (in all the preparations the hypodermis 
and other cellular tissues have shrunk and separated widely from 
the cuticle). 
As to the function and homologies of these structures it is diffi- 
cult to decide. I have never noticed that they give off any odor, 
though they may prove to be repugnatorial; they are not visible in 
the living insect, being concealed by the long dense hairs clothing 
the body; they are not spraying organs as they are imperforate at 
the end, not ending as the lateral eversible glands of Hyferchiria 
to, etc., in a crateriform orifice. 
There are three views which might be taken as to their homol- 
ogies. 
1. They may be merely fleshy papille like the short or long 
tubercles of the larve of Attacine and of certain Papilionide. 
2. They may be permanently everted glands, or osmateria, 
which have by disuse lost their power of retraction, and their cra- 
teriform opening, as well as the power of secreting a malodorous 
fluid. 
3. If it should ultimately be fully proved that Lepidoptera have 
temporary abdominal appendages, and that the proplegs or so- 
called abdominal legs, with crotchets, are merely secondary, adap- 
tive structures, then these may be pleuropodia, or homologues of 
the temporary embryonic abdominal legs of the lower insects. 
The first view is unlikely because in the larva of Attacus 
each lateral long horn-like process arises zz front of the spir- 
acle, on the prothoracic and second abdominal segments, and 
there are no such processes in a corresponding position on the other 
abdominal segments. Moreover the elongated fleshy or soft, flexi- 
+ Appendages of the first abdominal segment, etc., 1890. 
PROC. AMER. PHILOS. SOC. Xxx1I. 148.2 K. PRINTED FEB. 5, 1894. 
