REPORT ON THE CRUSTACEA MACRURA. 893 



The pleon has the first somite divided, as in the preceding species, into an anterior 

 and posterior section, but instead of the lateral walls being compressed, the antero-lateral 

 margin of the coxal plate is expanded outwards to an obtuse point. The second somite 

 is likewise divided into two portions, and the coxal plate projects both anteriorly and 

 posteriorly over the adjoining somites, the anterior margin of the former being armed 

 with a large, strong, sharp tooth that is directed obliquely forwards. The third and 

 fourth somites are subequal in length, dorsally smooth, and laterally compressed, the 

 compression increasing posteriorly. The fifth somite is shorter and laterally more com- 

 pressed than the preceding ; it is smooth in the median line, and on each side it is 

 dorsally armed on the posterior margin with a strong tooth. The sixth somite is 

 cylindrical, and twice the length of the preceding somite. 



The telson is subequal in length with the sixth somite, and slightly narrows 

 posteriorly, where it terminates in a straight line fringed with short hairs. 



The ophthalmopoda are pyriform, and are projected on a short stalk, the ophthalmus 

 being of slightly greater diameter than the peduncle. 



The first pair of antennas is enlarged at the base, and gradually narrows to a 

 cylindrical shaft that reaches beyond the rostrum, where it carries two short subequal 

 joints ; the terminal joint supports two short (broken) flagella. 



The second pair of antennas has a short flagellum that does not reach beyond the 

 apex of the rostrum (but this is probably due to the incomplete growth of the animal), 

 and carries a large and broad scaphocerite with parallel margins that is subequal with the 

 length of the peduncle of the first antennas, and is rigid on the outer margin, and distally 

 armed with a small tooth ; the inner is fringed with a series of hairs. 



The pereiopoda are all broken off at the extremity of the basisal joints, and the 

 ecphysis are also wanting. 



The pleopoda are short and in an incipient stage. 



The sixth pair is subequal in length with the telson, broad and foliaceous, and except 

 on the external margin of the outer plate fringed with hairs. 



Hectarthropus tenuis, n. sp. (PL CXLIV. fig. 6). 



Long and slender, carapace one-fourth of the length of the animal, anteriorly produced 

 to a rostrum that is smooth on the lower margin, and dorsally armed with three teeth at 

 the base. 



Pleon having the fifth somite smooth ; sixth somite subequal with the three preced- 

 ing somites. 



Telson half the length of the sixth somite. 



