1921.] Fauna of the Chilka Lake : Polychaeta. 655 



branchiae, though in much larger number, in the presence of a well-developed collar, 

 and in the shape of the abdominal crochets, and differs in the presence of caudal 

 eyes and in the shape of the abdominal capillary setae. L,eidy (torn, cit.) figures but 

 does not describe the collar of Manayunkia speciosa, and his figures are not decisive 

 as to the presence or absence of the dorsal indentation. Bush, however (1905, p. 188), 

 in a generic diagnosis of Manayunkia, says that the collar is entire, without in- 

 cisions or clefts. If this is the case it resembles Haplobranchus and differs from 

 F. spongicola. The latter reduces the gap between Manayunkia and Haplobranchus 

 on the one hand, and Fabricia on the other, and it has as much or as little right as 

 these forms to generic rank. All the characters cited above, which differentiate the 

 various forms, are probably only of specific rank, with the possible exception of the 

 simple or branched branchiae. In the latter respect the Chilka species agrees with 

 Manayunkia. The latter title has priority over Haplobranchus (1883), having been 

 described by Leidy in 1858, and it may itself be regarded as a sub-division of the. 

 genus Fabricia. 



Habitat. — Taken on two occasions, in the extreme south-west end of the Chilka 

 Ivake. On one occasion it occupied tubes embedded in the sponge Laxosuberites 

 lacustris, Annandale ; on the other, it was living amongst algae on the lower surfaces 

 of rocks on the shore. It was taken both in the fresh and salt-water seasons, but the 

 specific gravity of the water only varied from i - oo6-i'on. 



Family SERPUUDAE. 

 Genus Ficopomatus, gen. nov. 



This genus may, for the present, be defined by the following combination of 

 characters : — 



Modified setae present on the first thoracic segment, having blades provided, with very 

 stout teeth. Beneath the blades is a transverse row of more than two teeth. Uncini with 

 relatively few teeth, the lowest of which is in the form of an elongate bifid spine. Ventral 

 abdominal setae geniculate. Operculum fig-shaped, without any outgrowths. 



The modified setae of the first thoracic segment are very peculiar. They differ 

 from those of Serpula, Hydroides and Crucigera, in having teeth on the blade, and in 

 having more than two stout teeth below the blade. In these genera the stout teeth 

 are paired, whilst in Ficopomatus the largest tooth is median and unpaired. These 

 setae also differ markedly from those of Spirorbis, Chitinopoma, etc., which have a 

 crenulated wing below a finely serrated blade. The uncini resemble those of Poma- 

 toceros, S pirobranchus- and Pomatostegus in having few teeth, of which the lowest is 

 bifid, but Ficopomatus differs markedly from these genera in the shape of the oper- 

 culum and the modified setae of the first thoracic segment. 



Ficopomatus macrodon, sp. nov. 

 (Plate XXX, figs. 27A-M.) 

 Two small pieces of wood from the Cochin Backwater were covered with the 

 interlacing tubes of this species. The tubes form masses as in Hydroides norvegica, 



