(i) The head is small, triangular and lies at right angle to the longitudinal axis of the body.
(ii) The mouth parts are directed downwards so it is hypognathous.

S.No.	Tergum	Sternum
(1)	Dorsal surface is formed.	Ventral surface is formed.
(2)	Sclerites are also called tergites.	Sclerites are also called sternites 7th 8th and 9th
(3)	Male genital pouch is formed by 9th, 10th tergal and 9th sterna sclerites.	Sternites form female genital pouch.

(a) Clitellum Location: 14^th to 17^th segments appears as unsegmented externally
(b) Spermathecal openings: Location 6/7, 7/8 and 8/9 segments.

S.no. Peristomium Prostomium (1) It lies at the middle of the first
true segment It lies on pseudo or false segment (2) It starts to push the ingested
food into pharynx It starts ingestion (3) It serves as mouth A small flap overhanging the
mouth serves as upper lip

1. Cutaneous respiration: by skin
2. Lamellar or bronchial respiration (young and developing tadpole):- by external and internal gills
3. Pulmonary respiration: by lungs
4. Buccopharyngeal respiration: by buccal cavity

The bilobed mass of nervous tissue called supra - pharyngeal ganglia, lies on the dorsal wall of the pharynx in the ^3rd segment, is referred as the "brain". The ganglion found below the pharynx in the 4thseginent is called the sub-pharyngeal ganglion. The brain and the sub - pharyngeal ganglia are connected by a pair of circum-pharyngeal connectives. They run one on each side of the pharynx. Thus a nerve ring is formed around the anterior region of the alimentary canal. The double ventral nerve cord runs backward from the sub - pharyngeal ganglion. The brain along with other nerves in the ring integrates sensory inputs and command muscular responses of the body.

The earthworm has no special respiratory organs like lungs or gills. Respiration takes place through the body wall. The outer surface of the skin is richly supplied with blood capillaries which aid in the diffusion of gases. Oxygen diffuses through the skin into the blood while carbon dioxide from the blood diffuses out. The skin is kept moist by mucous and coelomic fluid and facilitates exchange of gases.

S.No	Hepatic caecae	Malpighian tubules
1	Found at the junction of foregut and midgut in the digestive system of cockroach	Found at the junction of midgut and hindgut in the digestive system of cockroaches.
2	They are eight finger-like blind tubular processes	These are about 100-150 yellow coloured thin filamentous structures.
3	They serve as digestive glands	They are the excretory organs of cockroaches.

1. They are eight finger like tubular blind processes called hepatic caecae found at the junction of foregut and midgut in digestive system of cockroach.
2. It acts as a digestive gland.

S.No	Anal cerci	Anal style
1	Paired, jointed filamentous structures.	Paired short and slender structures.
2	Present in male and female cockroach in 10th segment.	Present only in a male cockroach in the 9th sternum.
3	Acts as a sense organ and is receptive to vibrations in air and land.	This does not serve as a sense organ.