LEPTOSTRACA, SCHIZOPODA AND STOMATOPODA. 181 



South end of Cheval Paar, surface tow-net. One specimen, 5 rnillims. 



East Cheval Paar, surface tow-net. Two specimens, 5 '5 millims. and 7 rnillims. 



South end of Mutwal Island, surface tow-net. Seven specimens, 6 '5 millims. to 

 8 '5 millims. 



North end of Chilaw Paar, surface tow-net. Three specimens, 4 millims. 



Description of largest specimen:- 



The length of the largest specimen of this larva was 8*5 millims. from the eye 

 to the telson, or 11 millims. from the tip of the rostrum to the telson. 



Carapace with the rostrum very long and acute, its length measured from the 

 antero-lateral spine to its tip greater than the length from the antero-lateral spines 

 to the posterior border of the carapace ; six small spinules on the ventral edge of the 

 rostrum ; antero-lateral spines quite small ; postero-lateral spines long, extending 

 half-way along the telson, with a prominent spine at its base projecting ventrally ; 

 postero-median dorsal spine quite short ; dimensions of carapace, length from antero- 

 laterals to the posterior border, 3 '5 millims. ; antero-laterals to tip of rostrum, 

 4 millims. ; postero-lateral spines, 3 millims. 



Abdomen, with all the segments and their appendages developed ; first segment 

 hidden by the carapace ; postero-lateral angles of all the segments rounded ; sixth 

 segment without a pair of median dorsal spines ; appendages all well developed, and 

 setose, with the gills just appearing. 



Telson (fig. 41) about one-third as broad again as long; six marginal spines well 

 developed ; the margin between the submedians with two very prominent spines 

 dividing this part of the margin of the telson into three parts, each part deeply 

 emarginate, the central part slightly -smaller than the lateral portions and each 

 portion bearing seven spinules with very minute comb-like spinules in between ; 

 two intermediate and one lateral spinule present on each side. 



Uropods short, only as yet reaching to the lateral spines of the telson ; outer, edge 

 of external branch with two spines ; ventral prolongation of the uropods with the 

 two spines subequal in length. 



Raptorial claw (fig. 40) still without any signs of teeth below the integument ; 

 last three thoracic appendages present and biramous, but very small. 



The large number of larvae of this type present in the collection has enabled me 

 to trace, in a fairly complete manner, its life-history from the earliest stage, the 

 Erichthoidina, to the stage described above. The most important and interesting 

 changes are undergone by the carapace, and a study of these changes has led me 

 to differ from BROOKS in one or two points. A very brief description of larvae at 

 various stages may first, with convenience, be given. 



Larva 2 millims. (tip of rostrum to telson). This is the smallest larva of the 

 series, and represents the Erichlhoidina stage. The carapace is without any trace 

 of antero-laterals and there is no spine at the base of the postero -laterals. The 

 rostrum is quite short and without ventral spinules. The postero-laterals are also very 



