L 1 1 1 CEYLON PEARL OYSTER REPORT. 



Orchornenella, Sars, 1894. 



Orchomenella nana (Kroyer) = 0. ciliata, Sars, ' Amph. of Norway.' 



ChevalPaar; February, 1902; 30-40 specimens. 

 Length of male, 5'5 millims. 



Tryphosa, Boeck, 1870. 

 Tryphosa cucullata,* n. sp. Plate IV., fig. 8. 



Kondatchi Paar; 17th November, 1902; one male. Length 5*5 millims. 



Body compressed ; first 4 side-plates twice as deep as the segments, the 4th deeply 

 excavated behind ; the 5th deeper than wide. The 3rd pleon segment has the hind 

 and lower margins straight, the posterior angle bluntly rectangular ; the upper margin 

 produced in a subacute tooth behind. The 1st urus segment has a deep dorsal 

 depression with a subangular carina behind it. 



Head nearly as long as the 1st segment, produced in front; ocular lobe acute, 

 produced to the 2nd joint of the upper antennae. Eyes large, oval, red. 



Upper antennae : 1st joint tumid, projecting over the 2nd, which again completely 

 overhangs and conceals the 3rd. First joint of the flagellum fully as long as the 

 remaining 5, with about 10 rows of setules and a dense brush of long setae. 

 Appendage 5-jointed, not reaching the end of the 1st joint of the flagellum, the 

 joints subequal (fig. 8). 



Lower antenna? of the usual character of the males of this family, the flagellum 

 reaching the urus. 



Mouth organs and maxillipeds not examined. 



First gnathopods as in T. angulata, G. O. Sars, the palm very oblique. 



Second gnathopods : wrist much expanded below, without furring or setae ; lower 

 margin of the hand produced ; dactylus small. 



The last 3 pair of perceopods are subequal and have the 1st joints wide, smooth, 

 and rounded behind, spinous in front ; the 3rd joints are much expanded behind, 

 more so than in any of the species of Tryphosa figured by Sars. 



The 3rd uropods have the- rami widely lanceolate, rather longer than the peduncle, 

 and spinous on their inner margins ; they extend rather beyond the 2nd and as far 

 as the 1 st pair. 



Telson convex on the upper side, long, reaching to the middle of the 3rd uropods, 

 divided nearly to the base, with 2 or 3 submarginal spines and a larger apical spine on 

 each division. 



The single specimen was not dissected, but it is distinguished by the peculiar 

 hooded character of the peduncular joints of the upper antenna?, in which respect it 

 resembles the genus Ambasia, from which however, it differs in the form of the 1st 

 gnathopod. 



* From the hood-like character of the first 2 joints of the upper antenna'. 



