EXTERNAL ANATOMY OF INSECTS. 525 
per side of the head, I am next to consider the Szb- 
Jacies, or under side: but as the principal parts that oc- 
cupy this side have been already considered, I shall have 
no occasion to detain you long. 
i. Jugulum*.—This part, which may be regarded as 
analogous to the throat in vertebrate animals, lies between 
the cheeks ; from which it may usually be distinguished 
by being more lubricous and tumid, and often separated 
by an impressed line. It is particularly conspicuous and 
elevated in the Lamellicorn beetles, and calculated by its 
lubricity for easy motion in the lower side of the cavity 
of the chest. Its apex is the base on which the mentum 
sits. It is not necessary to enlarge further upon it, as it 
seldom exhibits striking characters. 
III. Collum®.—In a large proportion of insects the 
head inosculates in the trunk without the intervention 
of a neck, or a constriction of the head behind. In the 
Orders Orthoptera, Trichoptera, Lepidoptera, Hymeno- 
ptera, and Diptera, no instance of it that I recollect oc- 
curs: in the Coleoptera there are many. In the Preda- 
ceous beetles, though several have no distinct neck, yet 
others, as Anthia, &c. have a short and thick one; and 
some few, as Colliuris, Agra, &c. one more pronounced. 
Latreille has named a tribe in this Order Trachelides, - 
from the circumstance of their having a neck: in this 
tribe you will find the blister-beetles (Cantharis and My- 
labris) both of the moderns and the ancients. Jn the 
Hemiptera order the water-scorpions Nepa, &c. haye a 
thick short neck; and Selus, (a kind of bug,) one longer 
and more slender, and, like Raphidia the snake’s-head 
* Prate VI. m. > Tbid. 
