Gross anatomy of Watase's shrew, Crocidura horsfieldi watasei.

The Watase's shrew (Crocidura horsfieldi watasei) which is a native in the Nansei Islands in Japan, is one of the smallest mammalian species with 5-8 g of the body weight. Both males and females were caught in the field of the Amami Islands, and their internal organs in the thoracic and abdominal cavities were examined under the dissecting microscope and by the serial cross sections method. In comparison with the musk shrew belonging to the same subfamily Crocidurinae, the following features were basically similar; very short intestine in comparison with the body length, the absence of cecum, and the structure of the genital organs. Besides, the following were different; the small sized body, the small sized spleen compared with the body weight, and the cardiac glands limited in the end of the esophagus.