between those of these two species and it is quite remarkable that the locality where Nephr. 

 Sibogae has been taken, is situated between the Philippine Islands and New Zealand. Never- 

 theless, in my opinion, the validity of Nephr. Sibogae cannot be called in question. 



The largest male is 1S4 mm. long from tip of rostrum to the end of the telson, the 

 largest female 175 mm., while the two egg-laden females measure 128 mm. and 135 mm. In the 

 largest male the rostrum (PI. IV, fig. 18) reaches as far forward as the antennal peduncle, but the 

 distal extremity, beyond the tooth of the lower margin, is apparently regenerated, so that its 

 shortness is no doubt abnormal : in all the other specimens the rostrum slightly projects beyond that 

 peduncle. The rostrum presents the same form and the same armature as in NepJir. Thomsoni\ 

 the proximal half (PI. IV, fig. 18^/) is slightly declivous, the distal half obliquely directed upward, 

 so that the acute tip is situated in a line with the upper margin <>f the cephalothorax or slightly 

 above it. Just in the middle the lateral margins are armed with a small spine, which is directed 

 obliquely forward ; while the postenor half of the upper surface is concave, the distal upturned 

 half appears distinctly carinate, the carina gradually arising just in front of the lateral spines. 

 The carinate, lower margin of the rostrum is armed with an acute tooth a little beyond the lateral 

 spines and is situated a little farther distant from the tip of the rostrum than from the latter; 

 the three spines are of the same size. Like in NepJir. Thomsoni and Nephr. Challengeri, the 

 lateral margins of the rostrum are continued into two parallel ridges that reach backward to 

 near the cervical groove, but, otherwise than in these two species, in all our specimens of 

 Nephr. Sibogae the two ridges are armed with f our spines and not with three. The two spines 

 of the foremost pair are strong and very slightly directed outward, the three posterior pairs 

 which are considerably smaller, gradually decrease in size, so that the spines of the 

 penultimate pair are of the same size as the lateral spines of the rostrum and those of the 

 last pair still smaller. Just in front of the penultimate pair of spines one observes, like in 

 Nephr. Thomsoni and like probably also in Nephr. Challengeri, a small tubercle in the mid- 

 dorsal line of the carapace, from which tubercle a low and obtuse carina runs forward to the 

 rostrum and backward to near the cervical groove ; that part which is situated posterior to the 

 tubercle, is flattened and slightly broader than that which runs in 'front of it. On each side 

 of this sometimes rather inconspicuous crest and contiguous to it, one observes, in the middle 

 between the two large spines of the foremost pair, a very small, low and rounded tubercle or 

 elevation ; these two small tubercles are often inconspicuous. The flattened and compressed 

 antennal tooth is large and acute like in Nephr. Thomsoni '\ the anterior part of its outer 

 margin is directed straight forward, or slightly outward or slightly inward and posteriorly it 

 gradually curves inward towards the hepatic groove. On a somewhat lower level than the 

 antennal spine one observes, immediately behind the hepatic groove, a small acute spine, like 

 in the two other species; this spine has about the same size as the lateral spines of the rostrum. 

 The hepatic groove is quite distinct; it is directed obliquely upward, more or less S-like curved, 

 towards the 4 th or last pair of post-rostral spines, but it reaches only to just beyond the middle 

 of the distance between the hepatic spine and the post-rostral ridge. At the upper end of the 

 groove there is a very small spine, much smaller than the hepatic spine and about of the same 

 size as the 4* pair of post-rostral spines; between this small spine and the hepatic spine in 



