The circulatory system, lying in the mid-dorsal line of the body, consists of an oval heart, the ophthalmic artery, and a dorsal abdominal artery. The digestive system comprises a wide, large alimentary tube and ''two pairs of digestive glands. An oesophagus, a proventriculus, midgut, and a short proctodaeum or hindgut form the digestive tube. The digestive glands are very well developed and are beaded in form; each pair lies on either side of the alimentary canal. The reproductive organs are well developed in both sexes in the male they consist of paired testes and their vas deferentia, and in the female paired bilobed ovaries and oviducts. A cerebral or supraoesophageal ganglion, a suboesophageal ganglion, and 7 thoracic ganglia form the nervous system. The supraoesophageal ganglion is united with the suboesophageal ganglion by means of the circumoesophageal commissures, whereas the thoracic ganglia and suboesophageal ganglia are linked with each other by paired connectives. The gills and the tracheae are the organs of respiration. The gills are borne of the bases of the pleopods and are enclosed in the branchial chamber. The tracheae are located on the lateral lobes of the 1st 2 pleopods only.