very large; eye-stalks of very moderate length. Antennular peduncle with the third joint not 

 shorter than the first. Antennal squama lanceolate, with setae along both margins and a distal, 

 transverse suture. Labrum (PI. XI, fig. 3a) with a long, spiniform process from the transverse 

 front margin. Left mandible (PI. XI, figs. 3/; and 3^) with the masticatory parts well developed: 

 the incisive part not much produced with the margin dentate, the movable lobe very thick, 

 three extremely broad setse with setiform branches along their front margin, and the molar 

 process thick. The palp is similar in both mandibles and extremely curious (figs. T,d and T,d)\ 

 first joint is as usually extremeh' short ; the second joint is long, with the distal two-thirds of 

 its inner side .somewhat expanded, strongly chitinised and quite flattened, the margin of this 

 part as a whole straight with almost a score of oblong-triangular, very sharp and quite regular 

 saw-teeth, the whole portion described being a most perfect saw acting against the saw of the 

 opposite palp; third joint is short and narrow. Maxillulse (PI. XI, fig. 2>e) with a produced, 

 rounded protuberance on the front side of third joint (essentially as in Stilouiysis gt-andis Goes, 

 in which the protuberance is angular). Maxilla; (PI. XI, fig. 3/) nearly as in Stilomysis Norm.; 

 lobe of second joint with an e.xtremely robust seta at the inner base of its distal part; terminal 

 joint of the palp oval; e.xopod somewhat small. Maxillipeds (PI. XII, figs. 2c and 2d) nearly 

 as in Heminiysis G. O. S. ; second joint very long, with a somewhat narrow, moderately long 

 lobe; the two following joints with their inner margin convex but without any real lobe; claw 

 very slender, setiform. Gnathopods (PI. XII, fig. 2c) in the main as in RIysis (Prajiiats) flcxuosa 

 O. F. Miiller, without distinct claw. First pair of thoracic legs (PI. XIII, fig. 2/) moderately 

 slender; sixth joint divided- into three subjoints; seventh joint moderately small, slender; claw 

 completely setiform. 



Pleopods in the male immature specimens small, biramous, with the exopod increasing 

 In length backwards, being on the anterior pairs .shorter, on the fourth pair somewhat longer, 

 than the exopod, on the fifth pair twice as long as the exopod, but very far from developed. 

 Uropods (fig. 2g) somewhat slender, with the endopod only a little shorter than the exopod; 

 both rami with setje along both margins and without spines; otocyst very large. Telson (fig. 2^) 

 long; the basal part short and decreasing considerably in breadth, with 2 pairs of .short, lateral 

 spines; the remainder widening slightly in the proximal third and then tapering feebly to the 

 end which is moderately broad, very feebly convex and armed with 4 very long and extremely 

 robust spines; the spines of the inner pair a little removed from each other and the interval 

 with 2 very small, slender spines; a little more than the distal half of each lateral margin 

 furnished with numerous, moderately small spines (fig. 2//), which seen from above (fig. 2g) are 

 nearly hidden by a row of long and very robust spines originating from the upper surface of 

 the telson near the margin. 



Remarks. — The saws on the second joint of the mandibular palps are certainly an 

 auxiliary instrument for dealing with the food. By these saws and the telson having two rows 

 of spines at each side this genus is excellently distinguished from all other forms of the entire 

 family. The mouth-appendages and thoracic legs are essentially as in the tribe Mysini, but the 

 long process on the labrum is not known in any member of the tribe or even of the subfamily 

 Mysinae, while it is found in two other subfamilies, viz. Siriellinae and Gastrosaccinae ; the shape 



