530 C. H. RICHARDSON 
may be a respiratory apparatus, but Kulagin (’98) was led to 
the conclusion through experimentation that its funetion is excre- 
tory. He injected a mixture of carmine and indigo-carmine into 
the body cavity of Apanteles (Microgaster) glomeratus and after 
two or three hours the presence of indigo-carmine could be de- 
tected in the cells of the caudal enlargement as well as in those 
of the Malphigian tubules, showing that the former possessed 
the power of removing waste substances from the blood. As 
is stated below, the larval stages of Spalangia are entirely with- 
out a functional tracheal system or any structure resembling a 
respiratory organ, yet it suffers no inconvenience through this 
deprivation. The caudate larva lives in a medium abundantly 
supplied with oxygen and there is reason to believe that it re- 
ceives oxygen along with its food or directly through the cuticula 
without the aid of a specialized respiratory organ. 
The name planidium, first suggested by Dr. Wheeler, has been 
used by Smith (’12) to designate the young larva of Perilampus 
hyalinus Say. This is an active, free moving creature, heavily 
chitinized, with a distinct head segment, antennae and mandibles 
and a few spines on the dorsum. There may be a pair of long 
cerci on the anal segment as in Perilampus hyalinus and Orasema 
viridis, or they may be absent as in Leucospis gigas. On the 
ventrum of Perilampus are spiny processes and rows of simple 
spines, while on the ventrum of Leucospis each body segment 
except the last bears a pair of long spines, each individual spine 
of which is situated on a short basal process. A less specialized 
type is seen in the planidium of Spalangia, described below, in 
‘which spines are wanting. The planidium larva appears to be 
restricted to the superfamily Chalcidoidea and to those species 
in which the first stage larva leads an eco existence at 
least temporarily. 
Another larval type occurs in the Giallo and has been 
found by Silvestri in Oophthora semblidis. I shall call it the 
oophthoraform larva. It is perhaps less distinct than the others, 
approaching more nearly the typical hymenopterous larva. Com- 
pared with the larval form into which it finally develops, it has 
a smaller mesenteron and a larger stomenteron and proctenteron. 
