194 MODERN CLASSIFICATION OF INSECTS. 
which, doubtless, serves them instead of feet. The clypeus and upper 
lip are distinct and transverse (fig. 81. 18. front of head; 19. ditto 
sideways ) ; the mandibles horny and tridentate, the maxillz and labium 
short, and formed of fleshy lobes soldered together without any palpi; 
the labium having three minute tubercles, the central one being evi- 
dently the organ from which the silken threads are discharged for the 
formation of the cocoon. Exclusive of the head, the body is composed 
of thirteen segments, (numbered in my figures from 1 to 13,) the first 
and second of which are furnished at their posterior lateral margins 
with a pair of spiracles ; and the 4th, 5th, 6th, 7th, 8th, 9th, 10th, and 
11th have also a pair of spiracles placed on their anterior margins, 
so that there are twenty spiracles in the whole. The larva, when first 
I examined them, were enclosed in an oblong-oval case of a thin papy- 
ritious appearance, and of a pale reddish brown colour (jig. 81. 20.), to 
the outside of which the remnants of the flies, which had served for 
the support of the larva, were attached. It is proper to state, in con- 
sequence of an observation made by Mr. Shuckard in a note to Bur- 
meister’s Manual Transl., p. 357., that both sexes of the Crabro 
were reared by me from larve precisely agreeing in the number of 
their segments. (See Zrans. Ent. Soe. vol. ii. p. 127.) 
M. Walckenaer states that there are three species of small Crabros 
with the face silvery, which constantly endeavour to enter parasitically 
into the cells of Halictus, two of which he names C. punctatus and C. 
crassipes. (Mem. Halict. p. 35.) 
The genus Trypoxylon Laér., at once distinguished by its reniform 
eyes ( fig. 82.9.) and long abdomen, was considered by Saint Fargeau 
(Enc. Méth. tom.x. p.'749.) as parasitic; and consequently that its 
name, given to it in allusion to its wood-boring habits, was inapplicable. 
The Linnean account of its habits, as observed by Bergman (Syst. Nat., 
vol. ii. p. 943.), is, however, substantially correct, as I have clearly 
proved by some facts published in the 7rans. Ent. Soc. vol.i. p. 205. ; 
although, from having repeatedly seen it enter the burrows of other 
insects, I was at first induced to adopt the notion of St. Fargeau. Its 
object, however, I subsequently found was evidently to make use of 
the holes of other insects commenced in wood-werk, by first enlarging 
and then plastering them with a coating of fine sand. The prey of 
T. figulus is a small spider, which appears to me to be the young of 
Epeira diadema. Mr. Kennedy (Lond. and Ed. Phil. Mag., Jan. 
1837) also observed it carrying spiders, varying greatly in size, into 
