Abstract.-We examined factors affecting fish entrainment at California's State Water Project and Central Valley Project, two of the largest water diversions in the world. Combined, these diversions from the upper San Francisco Estuary support a large component of the municipal and agricultural infrastructure for California. However, precipitous declines in the abundance of several estuarine fish species, notably the threatened delta smelt Hypomesus transpacificus, have generated major concern about entrainment as a possible cause of the declines. We examined a 13-year data set of export pumping operations and environmental characteristics to determine factors affecting entrainment (as indexed by salvage at fish screens) and the potential for manipulation of these factors to improve conditions for fish. Entrainment of three migratory pelagic species-delta smelt, longfin smelt Spirinchus thaleichthys, and striped bass Morone saxatilis-was primarily determined by the seasonal occurrence of particular life stages close to the export facilities. We also found that the direction and magnitude of flows through the estuary and to the export facilities were reasonable predictors of pelagic fish entrainment. Entrainment of resident demersal species (prickly sculpin Cottus asper and white catfish Ameiurus catus) and littoral species (Mississippi silverside Menidia audens and largemouth bass Micropterus salmoides) was not explained by diversion flows, although large numbers of individuals from these species were collected. Our study suggests that entrainment of pelagic species can be effectively reduced by manipulating system hydrodynamics.

Letters to the Editor Synchronous multiple lymphomatous polyposis and adenocarcinomata in the large bowel Sir, The occurrence of multiple primary malignancies is well-recognised: most cases have involved two or more carcinomata, often of the skin, stomach, colon or breast, and most commonly found in the same organ homolaterally or contralaterally. Cases of synchronous carcinoma and a non-epithelial neoplasm are rarer but still well-documented. Synchronous adenocarcinoma and lym

Twelve anglers fishing in a UK navigation canal for a total of 42 h caught 567 fish, mainly gudgeon, Gobio gobio (L.) (n=306) and roach, Rutilus rutilus (L.) (n=253) at an average catch rate of 13.4 fish angler‐h−1 or 128.5 g angler‐h−1. The species and size of fish caught were compared with the numbers determined by depletion estimates at six sections of canal using micromesh seine netting. Fifty four percent of fish caught in the net were < 60 mm FL. Gudgeon (60–99 mm) were over‐represented in the anglers' catches whilst roach (60–99 mm) were under‐represented. The size distribution of roach and gudgeon caught by anglers using two types of bait (small maggots and chironomid larvae) was examined and smaller fish were found to be caught using the latter.

A 73 year old woman with cutaneous neurofibromatosis developed colonic carcinoma. The resected colon also contained multiple tubular adenomas and a polypoid ganglioneuroma. Multiple neurofibromas were seen during the operation over the serosal surface of the small intestine. Other cases of colonic ganglioneuromas and of combined neurogenic and epithelial colonic tumours are reviewed.

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