256 CEYLON PEARL OYSTER REPORT. 



and capitate papillae to which the foreign particles adhere. The anterior pair of 

 elytra probably meet or overlap, but in general the elytra are confined to the sides of 

 the body, leaving the mid-dorsum free. Nevertheless the latter is covered with sand 

 grains which adhere to dermal capitate papillae (Plate I., fig. 33). 



The prostomium, carrying two pairs of eyes, is overshadowed by the massive 

 ceratophore. There are no paired antennae on the prostomium, these having become 

 adnate to the cirrophores of the buccal segment which carry the tentacular cirri and 

 bundles of plumose setae (Plate I., fig. 34). The lower side of the ceratophore 

 carries a pair of dermal folds or lobes, which project from the sides below and 

 inwards. The ventral surface is not encrusted, but is thickly beset in each segment 

 with transverse rows of not very long acuminate papillae which are continued upon 

 the ventral surface of the parapodia. The ventral middle line is depressed. Amongst 

 the bases of the acuminate papillae are scattered minute globular papillae reminding of 

 those present in Hermione. The cirrophores (appendages of buccal segment) lie 

 between the palps and the head, so that it is difficult to remove a cirrophore without 

 the palp of the same side ; the palps are glabrous. 



The simple plumose setae of the buccal segment have been mentioned above. In 

 the second segment in addition to the plumose setae there are compound setae of the 

 form represented in Plate II., fig. 36, with filiform apex of the appendix, the shaft 

 being plumose. The ventral cirrus of the second segment is stout and long, nearly 

 twice as long as the parapodium, and arises from a distinct basal joint. In the third 

 segment compound setae of more usual form appear, the shafts being stout and 

 smooth except towards the extremity where they are squamose (Plate II., fig. 37) ; 

 the appendices are lost. The dorsal cirrus of this segment has the articulated 

 structure shown in Plate II., fig. 35. In the fourth segment the shafts of the 

 compound setae are still squamose distally ; the appendix is elongated, curved at 

 apex with a slight truncation jutting out below the apex. In a parapodium of a 

 normal body-segment (anterior third of body) there is a dense dorsal fascicle of finely 

 plumose capillary setae, followed by a superior ventral group of moderately stout 

 compound falcigerous setae with subelongate appendices ; then a central group of 

 stout compound setae with shorter appendices ; finally an inferior ventral group 

 of slender setae with elongate appendices (Plate II., figs. 38 and 39). Sometimes 

 the apex of the appendix is clearly bidentate, varying from this condition to smooth 

 (Plate II., fig. 40). The ventral border of the parapodium is beset with acuminate 

 filiform papillae and some spheroidal papillae (Plate II., fig. 41). The elytra are 

 notched and lobed, especially at the inner border (Plate II., fig. 42). 



Psammolyce rigida, Grube Plate II., figs. 44 to 47. 



GRUBE, 1868, ' Ann. Roth. Meer.' (Frauenfeld) ; ' Verh. zool.-botan. Ges. Wien,' p. 631, 1878 ; 

 ' Ann. Semp.' (Philippines), p. 55. 



Locality: Station LIIL, 10 miles north of West Cheval Paar. Three specimens, 



