84, Mr. A.S. Packard on the Development 
lying on each side of the labrum with its palpi and the maxille. 
These appendages do not as yet project much beyond the an- 
tennz, being short and papilliform, preserving the general form 
of the same organs in the larve. 
At this period the elements (sterno-rhabdites, Lacaze-Duthiers) 
composing the ovipositor he in separate pairs, in two groups, 
exposed distinctly to view. The ovipositor thus consists of three 
pairs of slender non-articulated tubercles arising on each side of 
the mesial line of the body, in juxtaposition. The first two pairs 
arise from the eighth abdominal ring, and the third pair grow 
out from the anterior edge of the ninth ring. The ends of the 
first pair scarcely reach beyond the base of the third pair. With 
the growth of the semipupa the terminal or tenth ring decreases 
in size, the tip of the abdomen is gradually incurved towards 
the base (fig. 2), and the three pairs of rhabdites approach each 
other so closely that the two outer ones completely ensheath 
the inner, until a complete distensible tube is formed, which 
gradually is withdrawn entirely within the body (see fig. 4). The 
male genital organ is originally composed of three pairs of non- 
articulated tubercles, all arising from the ninth abdominal ring, 
being sternal outgrowths, and placed on each side of the mesial 
line of the body, two being anterior and very unequal in size, 
and the third pair nearer the base of the abdomen. Thus, in 
their position, the three pairs of tubercles destined to form the 
male intromittent organ cannot be said to be strictly homological 
with the female ovipositor; nor can the external genital organs 
be considered in any way homologous with the limbs, which 
are articulated outgrowths budding out between the sternal and 
pleural pieces of the arthromere*. This view will apply to the 
genital armature of all insects, so far as I have been able to ob- 
serve. Itis so in the larva of Agrion, which completely repeats 
the structure of the ovipositor of Bombus in its essential features 
detailed above. Thus in Agrion the ovipositor consists of a pair 
of closely appressed ensiform processes which come out from 
under the posterior edge of the eighth abdominal ring, and are 
embraced between two pairs of thin lamelliform pieces of similar 
form and structure, arising from the sternite of the ninth ring. 
These sternal outgrowths do not homologize with the long, fili- 
form, antenna-like, joimted appendages of the tenth ring, as 
seen in the Perlide and most Neuroptera and Orthoptera, which, 
* This term is proposed as better defining the ideal ring or primary 
zoological element of an articulate animal than the terms somite or zodnite, 
which seem too vague; so also the term arthroderm for the outer crust or 
body-walls of Articulates, and arthropleura for the pleural or limb-bearing 
region of the body, being that portion of the arthromere comprised between 
the tergite and sternite. 
