112 ENTOMOLOGICAL SOCIETY 
Each of the following ventral sclerites. with the exception of the last, 
bears a pair of stigmatic openings which lead to the lung-books, and which 
are considered the invaginated external respiratory organs of an inferior 
class of Arthropods. I will state here my opinion in regard to the lung- 
books and the combs, without going into detail or endeavoring to prove it : 
The respiratory organs, which are now concealed in the abdomen, were 
in a prototype originally outside of the body, and much larger in size and 
in five pairs ; that the first pair, by being situated nearer the genital appa- 
ratus, became gradually stimulated, and, consequently, hypertrophied, with 
an increased blood and nerve supply, until they became so large that they 
were retained either as a necessary or important accessory to copulation, 
or a pleasant excitor in the voluptuous play of love-making. 
The last great region, the metasoma or tail, is by rights not a tail but a 
part of the abdomen, that is, it contains internally the proctodeeum or 
colon, the large caudal artery and the spinal cord with its four caudal gan- 
gliaorgans which are not found in a tail sensu proprio It is only its 
form that distinguishes this region from the mesosoma. This part is al- 
ways much longer and more slender in the male than in the female. 
The legs of the Arachnids are generally composed of seven principal 
joints, as follows : coxa, trochanter, femur, patella, tibia, metatarsus, and 
tarsus. We see that here a knee-joint, patella, is inserted between the fe- 
mur and the tibia. This knee-joint distinguishes the leg of the Arachnids 
from that of the insects, in which the tibia immediately follows the femur. 
In the Scorpion we find that the joint which follows the femur cannot be 
a knee-joint on account of its form, size, and articulation, but that it cor- 
responds exactly with the tibia of the insect leg. In other words, in the 
structure of the leg of the scorpion we find a proof of the closer relation- 
ship of that highly organized Arachnid with the next higher developed 
class of insects. 
Mr. Schwarz exhibited the following species and made remarks 
upon them : 
i. The species of insects referred to by Mr. J. B. Smith in his article, 
" Ants' nests and their inhabitants" (Amer. Natur., 1886, p. 686), viz., 
Tapinoma sessile (family Formicidce), an unnamed Heteropterous larva, an 
undescribed Anthicus (family Antkicidae), and the two species of Temnop- 
sopJnis (family Ma lachiida*). All these species occur under the same con- 
ditions on low plants in the prairie regions of southern Florida and, 
although belonging to three different orders, exhibit a remarkable resem- 
blance in general appearance. This holds especially true of the three first- 
named species. As another curious example of accidental resemblance, 
Mr. Schw r arz exhibited specimens of Olibrus princeps (family Phalacridce), 
Exochomtis marginipennis (family Cocctnellidce). and Argopistes scyrtoidcs 
(family Chrysomelidfe}, which occur promiscuously on shrubbery in the 
semitropical portion of Florida. 
