274 CEYLON PEARL OYSTER REPORT. 



First pair of natatory legs shorter and stouter than those of P. ovale ; the hasal 

 joint of outer branch bears 2 small elongated processes in place of spines. Basal 

 joint of 5th pair produced on one side into a long linear projection with apical spine ; 

 outer joint elongated, narrowing towards apex, armed with strong plain and plumose 

 spines. Two specimens, both females, were found in the Muttuvaratu pearl oyster 

 washings. It differs from P. ovale in the anterior antennas, the 5th pair of legs, and 

 particularly in the arrangement of the chitinous bands or reticulations of the carapace. 



Peltidium speciosum, n. sp. — Plate XIII. , figs. 12 to 17. 



Length, female l'l millim. ; male unknown. 



Body resembles P. angulatum in shape, but is differently reticulated, the chitinous 

 bands being thicker. Anterior antennas stout, 7 -jointed, the filaments and setae as in 



n * • • *, +• i • 1. 2. 3. 4. 5. 6. 7. 



the two previous species ; the proportional sizes are : 



Z"Z. A'Z. 14. u. o. o. D. 



First pair of natatory legs veiy robust. In other respects they and the other pairs 

 agree with P. angulatum. Fig. 17 represents a smaller form with thinner bands. 



A number of specimens, all females, were found in the Muttuvaratu pearl oyster 

 washings. The jointing of the anterior antennas, and the robustness of the 1st pair 

 of natatory legs, serve to distinguish this species. 



Peltidium serratum, n. sp. — Plate XIII. , figs. 18 to 22. 



Length, female 1*6 millim. ; male unknown. 



Body robust, rostrum broad, with 4 indentations on anterior surface ; margins of all 



the cephalothoracic segments serrated. Anterior antennas 6-jointed, the proportional 



1 2 3. 4 5. 6. 

 lengths of the ioints being: as follows • - 



& J b 20. 20. 14. 4. 4. 7. 



Outer branch of 1st pair of natatory legs robust. Fifth pair foliaceous, 1 -jointed, 

 with a long spear-shaped plumose apical spine and several lateral spines, some of them 

 plumose ; anteriorly drawn out into a curved protuberance with terminal spine 

 representing a rudimentary basal joint. 



Three specimens, all females, were found in the. bottom tow-net at Chilavaturai, 

 Ceylon. The character of the reticulation on the carapace and the remarkable 

 5th natatory legs clearly distinguish this species from others. 



Peltidium perplexum, n. sp. — Plate XIII. , figs. 23 to 27. 

 Length, female l'l millim. ; male unknown. 

 Body and character of reticulation resemble P. speciosum. Anterior antennas 



» • ■ j j m .- , i , „ • ■ , • , « 1. 2. 3. 4. 5. 6. 7. 



7-jointed, the proportional lengths of joints being as follows : — 



23. lb. y. o. 4. 3. 7. 



Natatory legs similar to those of P. angulatum. 



Two specimens, both females, were found in the Muttuvaratu pearl oyster washings. 



This differs from other species chiefly in the proportional lengths of joints of 



