342 "ENDEAVOUR" SCIENTIFIC RESULTS. 



spine. The sixth somite is a little shorter than the 

 telsoii, which is as long as the inner branch of the 

 uropods. 



The other females of this lot (Plate Ixi., fig. 2a-b, 

 Plate Ixviii., fig. 2n-b) are about of a size, being 49 and 50 

 mm. long respectively. The rostrum of the larger is 7 mm. 

 long and runs to the end of the second segment of the 

 antenmilar peduncle; it is armed with eight teeth, 

 including the epigastric tooth on the carapace, which is 

 as far from the second as the second is from the fourth ; 

 the second tooth is just in advance of the orbital margin ; 

 otherwise the rostral teeth are rather evenly spaced. The 

 stridulating organ is much as in the preceding specimen 

 and has but nine ridges. Behind the epigastric tooth 

 the carapace is not carinated. The carinatiou of the 

 abdomen is as in the largest specimen ; the inner branches 

 of the uropods slightly exceed the tip of the telson. 



The smaller of these two females, the one of 49 mm. 

 length, exhibits some differences which seem to be of 

 no great or specific importance. The chief reason for 

 figuring these females (Plate Ixviii., fig. 2a-b) was to 

 portray their rostral variation. In any good series of 

 P. stridulans, or as we now know it, P. novce-guinece, the 

 rostrum is somewhat variable, ranging from fairly 

 slender, straight, and uptilted ones as in the larger of 

 the two females described above, to those more or less 

 sinuous in general outlines and of greater depth as 

 shown in the smaller; in some specimens of "'stridulans"' 

 the upper margin appears quite concave, as in a 71 mm. 

 female from the Indian Museum. 



The rostrum of the 49 mm. female has but seven 

 teeth, of which the first, or epigastric tooth on the cara- 

 pace is as far from the second as it is from the fourth, 

 which in turn is farther from the third than this is from 

 the second; as a result the teeth appear quite unequally 

 spaced. The stridulating organ of this same specimen is 

 placed much lower than in the other specimens, and is 

 much less conspicuous; about eleven transverse ridges 

 can be counted. The carina of the second abdominal 

 somite shows no trace of a sulcus, and that of the third 

 somite is only faintly grooved, and hardly that, for in 

 its breadth dorsally it is just very slightly depressed 

 medially for a small fraction of its length near the 

 anterior end. 



