peduncle, scarcely six times as long as broad (fig. i c) ; terminal joint somewhat less than twice 

 as long- as broad. 



Male pleopods of first, second and third pairs are angular plates (figs. i k, i /, i m), 

 decreasing in length from before backwards, and each with some marginal setae; fifth pair 

 (figs. \p and \q) about as large as the second, with 8 setre. Fourth pair of pleopods reaching 

 a little beyond the end of sixth abdominal segment (fig. 12); distal peduncular joint (fig. \ n) 

 not twice as long as broad; exopod with the first joint four times as long as, and second joint 

 somewhat longer than, the third; the terminal branches (fig. 10) nearly equally long, a little 

 more than half as long as the third joint; inner branch with a short basal part thickened, the 

 remainder tapering to the end, and the proximal part of the distal half with setse along both 

 margins; outer branch two-jointed, with first joint slender and scarcely as long as the second, 

 which is shaped about as a slender spine. Sixth abdominal segment not much longer than the 

 fifth. Uropods (fig. ir) somewhat slender; exopod between seven and eight times as long as 

 broad, tapering feebly towards the end and considerably longer than the endopod. Telson 

 (fig. 1 r) as long as the sixth segment, half as long as the uropods and slightly more than 

 half as long again as broad ; to the description given above in the diagnosis of the genus may 

 be added, that it is equally broad a little behind the base and at the end, while it is a good 

 deal narrower somewhat beyond the middle; the posterior incision is rounded at the bottom, 

 and the whole posterior margin is furnished with 8 pairs of spines — the postero-lateral pair 

 not included — increasing conspicuously in length from the bottom of the incision to the outer 

 angles, furthermore the larger spines taper scarcely or slightly from the base to rather near 

 the end, which is rapidly acuminated; the distal half of each lateral margin of the telson with 

 5 normal spines increasing gradually in length backwards, but the fifth spine, which is found 

 on the terminal angle of the lobe, is yet somewhat small. 



Length of the single specimen, an adult male, 4 mm. 



Genera of uncertain Po si t ion. 



As already stated in a footnote on p. 13 I am unable to decide where the genus 

 Calyptomma Tatt. (1909) ought to be placed ; I am apt to think that it belongs to the tribe 

 Erythropini, but as it has been established on immature and badly preserved specimens, some 

 structural features are either unknown or imperfectly known. 



The "Siboga" collection contains 3 immature male specimens of a most interesting form, 

 on which I establish a new genus, Lycomysis, but as my knowledge is somewhat imperfect I 

 prefer to describe it here without deciding its systematic position and rank before the discovery 

 of the adult male, confining myself to a brief preliminary discussion in the "remarks" after the 

 diagnosis of the genus. 



Lycomysis n. gen. 



Description (based on the immature male). — Carapace with the frontal plate rather 

 short (PI. XII, fig. ia), posteriorly considerably emarginate, shorter than the carapace. Eyes 



