164 TRANSACTIONS OF THE 



which conceals the jaws when at rest. There are three pairs o£ mouth 

 appendages: the mandibles, or true jaws, which are single-jointed, and 

 are broad, short, solid, with a toothed cutting and grinding edge 

 adapted for biting. Behind the mandibles are the maxiUse, or acces- 

 sory jaws, which are divided into three lobes, the inner armed with 

 teeth, the middle unarmed and spatulate, while the outer forms a 

 five-jointed feeler called the maxillary j^f^dpus. The floor or back 

 side of the mouth is formed by the labium, or under lip, which is two- 

 . lobed and provided with a pair of three-jointed paljn. The lingua 

 (tongue) is a much modified organ, lying on the labium. The thorax 

 or breast consists of three closely united segments called the lyrotlw- 

 rax, mesotliorax and metathorax, or front, middle, and hind breast, or 

 thoracic rings. The upper region of the body is the notum or back, 

 the sides arepZeiM't677i, and the lower, sternum. 



The abdomen is composed of ten free-moving rings or segments,, 

 quite regular except the last one, which is much modified to form the 

 genital apparatus. On the side of each ring of the abdomen, as also 

 of the thorax, there are spiracles forming a row of ten breathing holes 

 on a side. The female abdomen tapers somewhat toward the end, ta 

 which is appended the rhabdites, two pairs of stout, corneous, hooked 

 spines forming the ovipositor. The anus is situated above the upper 

 and larger pair, and the external opening of the oviduct is between 

 the lower pair. Above the opening of the oviduct and between the 

 l^airs of rhabdites is a sharp fork, which aids in ovipositing. The 

 male abdomen is turned up at the end like the prow of a boat, and 

 in the genus Cahqnenus is enlarged, in others tapering slightly. It is. 

 provided with a pair of horizontally arranged pincers (cerci), for seiz- 

 ing the female. An extra and useless appendage is borne by the 

 "Spine-bearers," the ^cricZm-i, a spine, like a blunt thorn standing 

 out distinctly from under the neck. The other great group met with 

 here, the Q^dijjodini, are smooth-necked. 



INTERNAL ANATOMY. 



The digestive apparatus occupies the greater part of the cavities of a 

 locust's bodj^, accounting for the great amount of food they can eat 

 in a given time. The throat is short and curved, leading to the 

 immense crop, several conical valves closing the passage between to 

 prevent regurgitation. The crop is provided Avith folds, rows of 

 teeth, and a sweetish fluid, "molasses" thrown out by locusts when 

 seized. From the anterior end of the large, long stomach arise a 

 circlet of six large gastric cceca or pouches, whitish, pea-shaped, and 

 appendaged, each, by two long spurs, one pointing forward along 

 the crop, the other backward along the stomach. The stomach 

 extends from the first to the fifth abdominal segment, narrowing 

 into very simple and short intestines, the rectum provided with six 

 large, bottle-shaped glands, the oflice of which is unknown. 



The heart of an insect consists of a long tube lying just under the 

 back, having small- holes on the sides for the admission of the blood, 

 which is yellow or colorless, and which is prevented from escaping 

 by means of valves within. The heart is divided into several cham- 

 bers by transverse partitions, in each of which there is a valve which 

 allows the blood to flow from the hinder part forward, but not back- 

 ward, being forced finally from the forward part of the heart through 

 a canal to the head, from whence it returns and ramifies through the 



