1921.J Fauna of the Chilka Lake : Polychaeta. 639 



times swollen and bent, as in fig. 30A. The month forms a conspicnous opening on 

 the ventral surface (figs. 30c, 30D). It is surrounded by a thick folded lip, which is 

 richly ciliated. 



The thoracic segments, 3 in number, are provided on each side with a group of 

 capillary setae, 2-4 in number, and lateral in position. No hooks are present on the 

 thorax. 



The first abdominal segment is as long as, or a little longer than, the three 

 thoracic segments. The second abdominal segment is still longer, and is the longest 

 segment of the body. The succeeding eight segments diminish only very slightly in 

 length, but the three posterior segments are much shorter, especially the two last. 

 The anal segment is conical. All the abdominal segments are provided with dorsal 

 capillary setae and ventral hooks. The capillary setae are 1-5 in number. The 

 proximal part of the seta is smooth, the distal part spinous, but the spines are 

 so small that even under a magnification of 1300 diameters they are indistinct. The 

 thoracic setae are slightly thicker than those of the abdomen. 



In the ventral tori the hooks are arranged in irregular transverse rows. The 

 anterior segments contain 25-35 m eacn torus, the middle segments sometimes 

 55 _ 65, the posterior segments as few as 5-10. The hook (fig. 30E) has a straight 

 tapering shaft, a distinctly constricted neck, and above this a boldly curved bifid tip. 

 The teeth at the tip vary considerably in thickness, the two represented in fig. 27E 

 being the extremes. One hook is placed above the other, so that when seen from 

 above (fig. 30F) only a single tooth is visible. In the anterior abdominal segments 

 the setae are near the front part of the segment, but in the posterior segments they 

 are at the back. 



The head and buccal segment are almost entirely occupied by the buccal mass 

 (figs. 30c, 30D). Passing backwards from the mouth, and lying beneath the buccal 

 mass, is a clavate diverticulum, probably homologous with the "Lippen-organ " 

 described by von Dräsche in Omenta fusiformis, D. Chiaje, and later by Watson, but 

 not previously noted in Myriochele. The narrow oesophagus lies in the two anterior 

 thoracic segments. In the third thoracic segment it passes into a somewhat swollen 

 ' pharynx.' This is succeeded by the swollen intestine, which, in the first abdominal 

 segment, is composed of a mosaic of flattened granular cells, and differs markedly in 

 appearance from the succeeding and narrower part, though the transition in the 

 second abdominal segment is gradual. The intestine is full of organic debris, and 

 contains numerous diatoms, but no sand is present. A septum divides the buccal 

 from the first thoracic segment, and another lies between the second and third 

 thoracic segments. No septa could be distinguished in the anterior abdominal seg- 

 ments, but they are present in the posterior segments, just behind the bundle of 

 setae. In Owenia fusiformis all the segments, except the three thoracic, are separated 

 by septa. 



Five pairs of ' thread glands ' are present (fig. 30D), a pair in each of the three 

 thoracic segments and in the two anterior abdominal segments. The thoracic glands 

 are small, those in the third segment being the largest, whilst those in the abdominal 



