REPORT ON THE CRUSTACEA MACRURA. 



907 



side to a small, sharp, anteriorly directed tooth that stands upon the outside of the second 

 pair of antennae, whence the margin recedes obliquely backwards and outwards until it 

 reaches a sharp anteriorly directed tooth of larger proportions, that corresponds with 

 half the distance between the frontal margin and the oral apparatus ; from the outer 

 lateral tooth the carapace continues posteriorly to the extremity of the pereion, to which 

 it gradually narrows. 



The pleon consists of six somites and the telson. The pleopoda in our best-preserved 

 specimen are visible only as incipient buds, with the exception of the posterior pair, 

 which exists in a well-advanced condition and takes its character as part of the rhipidura 

 of the adult animal. 



The telson is long, tapering, and terminates in two small teeth, which converge distally. 



Habitat. — Pacific Ocean. 



The ophthalmopoda are large, pyriform, and projected on a slender cylindrical pedicle, 

 and pass on each side considerably beyond the lateral margin of the carapace. The 

 ophthalmus is equal in diameter to twice the broadest part of the pedicle, which originates, 

 one on each side of the great cephalic neural mass, in the centre of which on the dorsal 

 surface is a small black pigmented eye. 



The first pair of antennae consists of a peduncle and two short fiagella ; the peduncle 

 is only single-jointed, but at a short distance from the extremity there is a notch and a 

 small hair, and beyond it another small hair, each suggesting the point at which the 

 future articulations will occur. The fiagella are subequal in length and very nearly equal 

 in diameter ; they are both smooth and free from hair, but the outer supports two short 

 spines situated close together near the apex. 



The second pair of antennas has the two basal joints of the peduncle broad, the 

 second distally supporting a long scaphocerite that is narrow at the base, distally broad, 

 rounded at the extremity, the margin of which is fringed with long cilia, and the outer 

 maro-in is armed with a long and slender tooth. Beyond the second joint I can recognise 

 but a single robust joint that supports the slender flagellum, which appears to be long but 

 is broken off at about the length of the scaphocerite. In Milne-Edwards' figure it is 

 represented as entire and about half the length of the carapace. 



About one-third of the distance between the frontal margin and the first pair of 

 gnathopoda stands the epistoma, and posterior to it on each side are the mandibles, and 



