REPORT <>N THE CRUSTACEA MACRURA. 1 :! 



the animal is viewed laterally, are membranous from a little below the line which defines 

 the branchial from the hepatic region, and extend posteriorly beyond the line of the 

 posterior margin of the dorsal surface of the carapace. 



The pleon is longer than the carapace by about one half, but as the posterior portion 

 is generally folded beneath the body it looks shorter. The first somite is short and 

 triangular, having the broadest part situated posteriorly. It is nearly hidden beneath 

 the carapace, and does not support any coxal plates. The five anterior somites are 

 subequal in length, and rather broader than long. They are quadrate in their dorsal 

 . spect, and have a distinct line of demarcation separating the body of the somite from 

 the lateral or coxal plates, which are rounded at the anterior and posterior angles : they 

 have a longitudinal line of depression near the middle of each, and the margins are 

 fringed with delicate cilia. The sixth somite is also quadrate, and rather longer than the 

 fifth, it supports the coxal plates at the posterior angles, where they support a freely- 

 articulating joint that carries a pair of unequal branches. The seventh somite or telson 

 is divided into an anterior and a posterior portion by a free-moving joint near the middle. 

 The anterior portion is undoubtedly homologous with the somite, and the posterior with 

 its appendages, since the alimentary canal debouches at the posterior margin of the 

 anterior division. 



The ophthalmopoda consist each of a sharp-pointed ophthalmus situated at the 

 extremity of a large broad-based peduncle that gradually narrows to the apex ; the 

 peduncle is movable, but not to any very large extent, and is situated in a slight 

 excavation in the frontal margin of the carapace ; from the inferior margin of the eye 

 the metope falls perpendicularly, and on the outer side of it, immediately below and 

 outside the eye, is the first pair of antennae, which consists of three peduncular joints ; 

 the first or coxal is very long, reaching as far again as the distal extremity of the eye ; 

 in its length it curves downwards, and has the upper surface longitudinally excavated 

 to receive the second joint when folded back : on each side of the excavation is a strong 

 tooth — one on the outer side near the base, the other on the inner side at the distal 

 extremity; the second joint is about the same length as the first, but somewhat more 

 slender; it is nearly cylindrical in shape, and when folded back falls into the longi- 

 tudinal hollow of the first joint, the two spines acting apparently as guides to its 

 position : the third joint is shorter than the second, and is also cylindrical ; and when 

 the antenna is folded up it is directed forwards. At the extremity of this third joint 

 are situated two slender flagella; the primary branch is the longer and more robust, 

 being about twice the length of the third joint of the peduncle; the secondary branch 

 is about half the length of the primary. 



The second pair of antennae is implanted immediately outside the first. The first 

 joint supports a phymacerite that is curved inwards and downwards, impinging at its 

 extremity, which is serrate, against a small tubercle situated on the outer edge of the 



