412 DR. J. G. DE MAN ON CRUSTACEA CHIEFLY 



middle ; the first four are equidistant, the fifth is almost once and a half as long 

 as the fourth, and the sixth is as long as the fifth ; the tip of the sixth tooth 

 is tliree times as far from that of the fifth as from the extremity of the rostrum. 

 The rostrum is a little dilated distally, just below the sixth tooth, and carries here two 

 teeth, which are smaller than the first teeth of the upper border ; the first is situated 

 just below the middle of the sixth tooth, tlie second just below its tip, and the tip of the 

 second is a little farther from the extremity of the rostrum thau from the tip of the first 

 tooth. According to Stimpson, the lower margin should be armed with four teeth. 

 Posterior to the first tooth the lower margin appears slightly concave. Antennal spine 

 short ; pterygostomian spinule very small, but distinct. 



Abdomen rounded above, geniculate at the third segment, which is slightly produced 

 posteriorly into an obtuse lobe ; on either side of the middle the tergum of the third 

 segment carries a faintly impressed, longitudinal line, which runs from the posterior 

 border to a little beyond the middle. The pleura of the fourth segment, which is 

 a little longer than the fifth, ends in a small sharp spinule ; the sixth segment, once and 

 a half as long as the fifth and almost twice as long as broad in the middle, terminates, as 

 also the fifth, in a sharp tooth at the postero-lateral angles. The tapering telson, which 

 is one-third longer than the sixth segment, is armed on its flattened, upper surface with 

 four pairs of spinules and terminates in a small, sharp tooth ; of the two spines on each 

 side the inner are twice as long as the outer, which slightly reach beyond the median 

 tooth. The basal joint of the uropods, Avhich are a little longer than the telson, 

 terminates in a sharp tooth at its postero-external angle. 



The eye-peduncles, which carry a distinct ocellus close to the cornese, reach with the 

 latter beyond the lateral margin of the carapace. 



The internal antennae are little longer than the carapace and extend with half the 

 inner flagellum beyond the antennal scales. Their peduncle is as long as the rostrum 

 and reaches the middle of the antennal scales ; the first joint is somewhat longer 

 than the eye-peduncles when they are directed forward, and carries one or two 

 spinules at the distal border of its upper surface ; the large and broad stylocerite is 

 acuminate and reaches beyond the middle of the second joint ; the second joint, not quite 

 half as long as the first and as broad as long, is armed, at the autero-external angle, 

 with a strong spine, which is directed forward and outward ; the terminal joint, finally, is 

 half as long as the second and has a sharp tooth or spine at the distal end of its upper 

 border. The upper flagellum is considerably thickened along three-fourths its length 

 and the filiform terminal part extends bejond the scales. The basal joint of the 

 antennal peduncle carries a slender spine on the distal border of its lower surface; 

 the straight outer margin of the scale (PI. 32. fig. 32), which measures one-seventh 

 the whole length of the body, and is two and a half times as long as broad, terminates 

 in a sharp spine, which reaches a little beyond the rounded or truncate extremity of the 

 laminar portion. The antennal peduncle is as long as that of the inner antennae, and the 

 tiagellum is somewhat shorter than the body. 



The external maxillipeds, which are devoid of an exopodite, project with one-third their 

 terminal joint beyond the antennal scales. 



