REPORT ON THE CRUSTACEA MACRURA. 467 



dorsally protected by a small carapace that rises obliquely from the mandibular region 

 to the posterior margin of the pereion. 



The five anterior somites of the pleon are subequal in length and correspond to the 

 length of the pereion. The sixth somite is about half as long again as the preceding one, 

 is posteriorly produced to a small dorsal tooth, and has the under margin armed with 

 two strong teeth, the posterior of which is club-shaped and curved, and the anterior more 

 slender and pointed. 



The telson is about one-third the length of the sixth somite and terminates in a small 

 fork, the apices of which are armed with a small spine ; on the under surface in the 

 median line is a large protuberance, broad at the extremity and directed forwards. 



The ophthalmopoda are nearly as long as the cephalon ; the stalk is slender and the 

 ophthalmus bulbous. 



The first pair of antennae has the first joint of the peduncle nearly as long as the 

 ophthalmopod, whereas the second joint is short and reaches just to the extremity of the 

 eye ; the third is still shorter, and the flagellum is wanting in every specimen in the 

 collection. 



The second pair of antennae is likewise broken off at the extremity of the peduncle, 

 and supports at the base an extremely slender and pointed scaphocerite. 



The appendages of the mouth as well as the pereiopoda exhibit no specific character 

 that enables us to distinguish them from those of the preceding species. 



The first pair of pleopoda carries a large leaf-like petasma, has the anterior margin a 

 little below it armed with a strong blunt tooth, and terminates in a single multiarticulate 

 branch. The second pair of pleopoda carries at the extremity of the basal joint, between 

 the two multiarticulate branches, a strong blunt appendage. The third and two following 

 pairs of pleopoda are similar to the preceding, but they do not carry a similar appendage, 

 and each pair is successively shorter than the preceding. 



Females. — The female corresponds with the male in general proportions, but is usually 

 a Little smaller, although some resemble it closely in size. They can be readily dis- 

 tinguished by the absence of the large teeth on the inferior margin of the sixth somite 

 of the pleon, which are replaced by a small sharp tooth or point situated more posteriorly 

 than are the larger teeth in the male. The telson is also more slender and wants the 

 large tubercle that is so conspicuous in the male. 



Their appendages also correspond closely with those of the male, except the 

 pleopoda, which are simple and do not carry a petasma or tooth on the first pair nor a 

 tubular lobe-like appendage on the second, and the outer branch of the rhipidura has the 

 squamous portion produced as far as the extremity of the terminal tooth. 



Length, males and females, 10 mm. (0"4 in.). 



Habitat. — St. Paul's Rock ; North Atlantic ; Atlantic ; Tropical part of Atlantic 

 (at 200 fathoms, and at night) ; Fiji Islands ; Philippines ; Arafura Sea ; New 



