302 CEYLON PEARL OYSTER REPORT. 



segment, well-marked dorsally, obsolete ventrally. The third body-segment or second 

 branchiferous segment is evident above and below, and is produced outwardly into 

 two ear-shaped lateral lobes, between which there is a narrow rim representing the 

 ventral portion of* the segment. Behind this follows ventrally the first ventral 

 scute belonging to the fourth body-segment, which is at the same time the third 

 gill-bearing segment and the first setigerous segment. The fifth body-segment is 

 the first uncinigerous segment, and the uncini are arranged uniserially in the first 

 six pairs of uncinigerous tori ; the ten following tori carry uncini in two rows. The 

 twentieth body-segment is the last thoracic segment. Then follows the abdominal 

 region, which is destitute of capillary setae, the uncini being borne in single file upon 

 the abdominal pinnules. The first scutum differs from those which follow by its 

 large size and corrugated surface. There succeed to this nine plain scuta ventralia, 

 becoming narrower and longer behind. After this again the scuta become sub- 

 divided by transverse grooves, finally ceasing between the penultimate thoracic tori. 

 The posterior subdivided scuta present a dark colour in the preserved material 

 (Plate VI., fig. 154). There are 17 fascicles of capillary setae, which have a fibrous 

 internal structure, the fibres separating out when the seta is crushed or broken. 

 Some of the setae, however, which were presumably broken before death, show a clean 

 fracture. It may be noted in conclusion, that in one specimen the scuta between the 

 eighth and ninth uncinigerous tori are divided by a cross furrow. 



Loimia crassifilis (Grube). 



Locality : East side of Cheval Paar. 



One very small individual of 20 millims., including the tentacular cirri ; the latter 

 are banded as in L. armulifilis. There are ten clear scuta ventralia, after which these 

 become quite obscure, but the tori remain separated by a wide decreasing median 

 ventral tract to the end of the thorax. Uncini from the fourth torus 4-dentate, with 

 an occasional rudimentary fifth tooth at the apex ; from the biserial tori 4-dentate, 

 the fourth tooth small ; from the abdominal pinnules 5-dentate, namely, four clear 

 teeth and a rudimentary apical tooth. The above corresponds with Grube's 

 description ('Ann. Semp.,' p. 226), "uncini pectiniformes dentibus tororum 4," 

 although his specimen was a very large one. The abdominal region is slender and 

 even ; the thoracic region tumid ; about 67 segments. 



Loimia medusa (Savigny) Plate VI., figs. 155 to 159. 



Savigny, ' Syst. des. Ann.,' p. 86 (quoted from Grube, ' Ann. Semp.,' p. 228). 

 (1.) Three specimens from Aripu Coral Reef, about 80 segments, width of thorax 

 10 millims. ; total length nearly 90 millims., of which 30 millims. belong to the 

 thorax; abdomen subcylindrical, varicose, simply flexed (not spirally coiled), narrower 

 than thorax (Plate VI., fig. 155). Uncini from the first torus 6-dentate ; from the 

 third some 5-dentate, some 6-dentate ; from the fifth 5-dentate ; from the biserial 

 tori and abdominal pinnules 4-dentate. There are five pairs of tori behind the scuta 



