1921.] Fauna of the Chilka Lake : Polychaeta. 649 



of the intestine. It is folded, especially round the anus. The caudal ring is fringed 

 with short bluntly rounded cirri. The median ventral cirrus is stouter than the rest, 

 and 2-4 times as long. In 15 specimens examined, the number of cirri, including 

 the large ventral one, is as follows: — 24, 20 (2), 19 (2), 18, 17 (3), 16 (3), 15, 14 (2). 

 Sometimes several of the cirri are fused together, forming a flat plate. 



In setigerous segments 1-3 the parapodia are in the anterior half of the 

 segments, in 4-8 in the middle, and in the subsequent segments near the posterior 

 end. 



The three anterior setigerous segments have dorsally a double row of capillary 

 setae. They are longitudinally striated, with two narrow wings and slender tips. 

 Ventrally there is a single uncinus (fig. 22H) with a simple boldly curved tip. In the 

 two anterior bundles the setae are rather more numerous than in the 3rd. In the 

 4th setigerous segment the dorsal setae are similar, but fewer in number. Ventrally 

 there is a row of uncini, each with 5 teeth above the main fang (fig. 22K). In the 

 8th foot several of the dorsal capillaries have plumose tips (fig. 22j), the spinelets 

 being rather long. These setae are much shorter than the smooth capillaries. There 

 is a ventral row of 14 uncini. In the 10th segment there are 17 uncini, in the 17th 

 segment 14 uncini. In the anterior segments the row of dorsal capillary setae 

 gradually shortens as the setae become fewer in number, and at the same time the 

 papilla from which they emerge increases in length. It is low and insignificant on the 

 ist setigerous segment, but on the 5th or 6th it forms a distinct swelling. In 

 segments 1-9 the capillary setae form a transverse row. At the 10th segment the 

 row tends to be oblique, and this tendency increases till at the 15th segment the 

 setae form an arch above the uncini (fig. 22G). The latter are embedded in a long 

 narrow slit surrounded by prominent tumid lips. The uncini (fig. 22K) have 5 or 6 

 diminishing teeth above the main fang. Beneath the latter there is on each side a 

 bundle of bristles, but their point of attachment is not indicated by a prominent 

 boss, as in many other species. The uncini of segments 4-21 are all similar, and 

 there is no obvious difference between the uncini of the same foot. 



Habitat. — This species was taken in large numbers at 11 stations, all in the south- 

 west end of the lake, south of a line drawn from Patsahanipur to Nalbano. Usually 

 they were obtained by digging in mud or sand at the water's edge, but on three occa- 

 sions they were taken some distance off the shore, on a muddy bottom. As might 

 be expected from the habitat of this species, it was usually taken in the salt-water 

 season, when the water level was low, but on one occasion it was taken in the dredge 

 in the freshwater season. The specific gravity of the water ranged from 1*002- 



I'OII. 



Family STERNASPIDAE. 



Sternaspis costata, Marenzeller. 



(Plate XX, figs. 5A, 5B.) 



1879. Sternaspis costata, Marenzeller, p. 34, taf. vi, fig. 4. 

 1890. Sternaspis costata, Sluiter, p. 108. 



