IQ2I.] 



Fauna of the Chilka Lake : Polychaeta. 



583 



o 



two anterior, above and below the spine, and a posterior ventral group. They are all 

 homogomphs, with slender finely serrated terminal pieces, those in the lower anterior 

 group having shorter tips than the rest. The 2nd foot resembles the ist, except that 

 it is a little larger, the lobes are larger, and the setae more numerous. 



In the 7th foot (fig. 3D, and text-fig. 36) the dorsal cirrus is relatively smaller. 

 The dorsal ligule is larger and flatter, pointed at the tip, and filled with glands. The 

 dorsal setigerous lobe is long and cylindrical, rounded at the tip, and its base is 

 surrounded by a sheath or fillet, within which it can be retracted by powerful muscles. 

 It is penetrated almost to the end by . 

 the dorsal spine, the tip of which is 

 surrounded by a sheath of columnar 

 cells. There are three to five setae 

 in the dorsal division. The ventral 

 setigerous division remains as in the 

 ist foot, except that the setae are 

 more numerous, and apparently only 

 in two groups, and the ventral ligule 

 is relatively thinner. 



The 15th foot differs from the 7th 

 only in having the dorsal and ventral 

 cirri somewhat smaller, the dorsal 

 ligule rather larger and flatter, and 

 the lobes of the ventral setigerous 

 division thinner and more elongate. 

 The dorsal division has four setae, the 

 ventral division ten in the upper 

 group, sixteen in the lower group. 



At the 22nd foot a slight indenta- 

 tion appears in the tip of the elon- 

 gate dorsal setigerous lobe, and this 

 gradually deepens till in the 26th or 

 27th foot the bifid condition shown 

 in fig. 3e is attained. In smaller 

 specimens the change may be com- 

 plete in the 24th foot. A similar change occurs in T. bogoyawlenskyi, but accord- 

 ing to Fauvel only in the posterior segments, the exact position not being stated. 



In the 30th foot (fig. 3E, and text-fig. 3c) the dorsal and ventral cirri and the 

 ventral ligule are greatly reduced in size. The dorsal ligule is large and long, 

 pointed at the tip, and full of glands. The dorsal setigerous lobe is deeply bilobed 

 at the tip, the spine lying between the two lobes. Its tip, enclosed in the gland, 

 is shown in fig. 3F. The dorsal setae, eight in number, lie above the two lobes, 

 whereas Fauvel says that in T. bogoyawlenskyi they emerge between the two lobes. 

 The dorsal setae now differ markedly from those in the ventral division. The 



cu 



Text -FIG. 3. — Parapodial diagrams of Ty loner eis 

 fauveli, sp. nov. 



a. ist foot. b. 7th foot. c. 30th foot. 

 • = Homogomph setae with spiuose tips. 



