The Anatomy of Natrix vittata (L.)

MATERIAL AND PROBLEM For the investigation of the anatomical pattern of Natrix vittata, the same material was used as for the description of the life of this snake. A preliminary question was whether both groups from Surabaia and from Tjimahi may be used for statistical treatment as a single unit or if they represent different varieties. The animals are easily recognisable and there is no outward sign which would indicate a difference between the group from the eastern coastal plains and the one from the western hills although the distance between both localities is about 800 km. The range of the body length is for both groups the same, for adult males in Surabaia 341-441 and in Tjimahi 346-457, and for females 392-560 and 395-555. In none of the other measures did we find any real difference between the groups of these two localities, so that we feel justified in taking the lot together as a single variety for Java. LENGTH AND WEIGHT The difference in body length for both sexes shown by the curve of Galton can be measured by the averages for adult animals, males 397.4 ± 3.84 and females 453.2 ± 4.51. The difference is obvious. The figures for weight also show a sex difference, the females being heavier, 37.14 ±1.38 gram versus males 24.25 ± 0.86. The correlation between body length and weight is for females r = 0.79 or Z = 1.05 ±: 0.13, for males r = 0.67 or Z = 0.85 ± 0.13. In % of the body length the weight is for males 6 and for females 8.3, the latter are stouter. In the animals with a complete tail, the relation between tail length and total length is in both sexes the same, round 25 %, as we have seen before.