ON CRUSTACEA BROUGHT BY DR WILLEY FROM THE SOUTH SEAS. 669 



The rostrum apjjears to be composed as usual of slender mandibles between an 

 elongate upper and under lip. 



The first maxillipeds have the terminal joint longer but much narrower than the 

 basal, with a minute spinule below the middle, and two apical setae. 



The second maxillipeds have the basal joint powerful, irregularly oval, longer .than 

 the finger and nail ; the inner margin of the finger is rather more bulging in the male 

 than in the female. 



The furcula is entirely wanting, and of ventral subsidiary hooks on the carapace the 

 only representative seems to be a spinule near the base of the second antennae. It may 

 be noticed that in Caligus abbreviatus Kroyer speaks of the furcula as practically rudi- 

 mentary. Possibly this organ is less needed in abbreviated forms. 



First feet. These are slender, three-jointed, the second joint the longest, the third 

 short, with three plumose setae on the inner margin, the apex fringed with three little 

 spines and a seta. 



Second feet. The stout basal joint begins with a narrow neck, perhaps representing 

 a true first joint, the point of junction with the true second being marked by 

 a plumose seta. The base carries two three-jointed rami, the first joint of the 

 outer and the second of the inner being the largest. The inner ramus carries one 

 plumose seta on the first, two on the second, six on the third joint. The outer 

 ramus has an apical spine to each joint, successively smaller, its second joint has two 

 plumose setae and the third five. The whole armature is, as so often in this pair, of 

 conspicuous size and beauty. 



Third feet. The large and laminar, transversely oval, basal joint has the trans- 

 lucent wing of its outer margin divided into three portions, the middle one very small 

 between the two little rami. The outer ramus has a minute first joint, the second 

 joint with one plumose seta, the third with three such setae and some setules. The 

 inner ramus has a nninute first joint with one plumose seta, and a second joint with six 

 such setae, but two of them very small. 



Fourth feet. The slender second joint is considerably longer than the rather stouter 

 basal joint, it is tipped with two unequal setae, and has near the middle of the 

 outer margin a seta, marking the point at which in some Caligidae an additional 

 articulation occurs. The similarity of this limb to the first maxilliped is worthy of 

 remark. 



The linear egg-strings of the female are not so long as the body ; the eggs are 

 numerous, eighty or more in each string. 



The caudal plates are separated by the rounded apices of the caudal segment, 

 which are produced a little beyond them. The minute basal joint is marked by a 

 setule at its junction with the obliquely oval second joint, the margin of which is 

 furnished with three plumose setae, successively longer inwards. 



The length of the female is 4 mm., of the male, 2 5 mm. 



The specimens were taken at New Britain on Nautilus ■pompilius. Others were 

 labelled ' from N. macromphalus. Lifu. 1896-7 etc' 



Dr Willey informs me that the specimens occur " iu N. pompilius in the mantle- 

 cavity, and in iV. macrovi/phalus on the slimy convexity of the involuted portion of the 



88— 2 



