[None. Introduction starts as follows:]
The collection of Polychaetes of the Indian Museum, Calcutta, is a very extensive one, including upwards of three hundred species belonging to thirty different families. Indeed, with the exception of a few small groups, nearly all the families of Polychaetes are represented. The bulk of the collection consists of the material collected by the R.I.M.S. "Investigator", but a very large number of specimens was obtained by the officers of the Zoological Survey in the Gangetic Delta, in the Cochin Backwaters, Krusadai, Pamban, and other localities on the coasts of India; and from other parts of the Indian Ocean.
The coastal fauna as might be expected is generally much richer in species than the deep-sea fauna, for the conditions of life in inshore waters are much more varied and are influenced by many more factors than those on the still bottom of the ocean.
In brackish waters, modified and often very peculiar forms are plentiful. Out of thirty species collected in the Chilka Lake, the Cochin Backwaters and the Gangetic Delta, and described by Southern (1921), three genera and twenty-seven species were found to be new to science. In the collections of the Indian Museum I was lucky to find again and examine most of the species described by Southern. Taléh-Sap, or the Inland Sea of Singgora, a lake connected with the Gulf of Siam, though far remote from the Chilka Lake, which lies partly in Bihar and Orissa and partly in the Madras Presidency, presents a number of analogous conditions as regards variations of salinity. Its fauna was partially investigated by Annandale. The Polychaetes collected from this locality consisted of the following species already found by Southern in the brackish waters of India: Nereis glandicincta Southern, Nephthys oligobranchia Southern, Nephthys polybranchia Southern, Heteromastus similis Southern, Barantolla sculpta Southern and Ficopomatus macrodon Southern. The collection also yielded three new species: Nereis talehsapensis, Brada talehsapensis and the very singular Talehsapia annandalei which so far I have not succeeded in referring to any known family.