1909.] ox DECAPOD CRUSTACEA FROM CHRISTMAS ISLAND. 703 Eutherian condition of the postcaval vein. Furthermore the two veins may be compai'ed with the Didjelphys embryo figured by McOhire*, where the right cardinal collateral is immensely larger than the left-hand vein. This is one among many variations which occur in the venous system of the embryos, as well as the adults, of that marsupial. Both this variation in Didelphys and the adult condition in Orycterojnis appear to me to be an inter-mediate step in the reduction of the two veins found in Monotremes and Edentates to the single i-ight-hand postrenal postcaval of other Eutheria, I now turn to the branches of the postcaval vein. The renals are as is usual asymmetrical, the right-hand veins flowing into the postcaval a little anteriorly to those of the left side. There are two renal veins on each side, and those of the left ai"e connected by an obliquely running joining vessel. Of these two latter vessels the anterior arises from the postcaval vein, where it is single, and the posterior from the slender left postcaval. It is very important to notice, from the point of view of a comparison with other Edentates, that the renals are quite unconnected with the spermatic veins. ISTo recognisable branch appeared accom-panying the ureter. The spermatic veins themselves, as is shown in text-figure 225, are quite symmetrical with each othei* and arise each from its own postcaval vein about half-way down between the i-enal and the posterior bifurcation of the postcaval. There is no caudal plexus and the veins are not so massive as in various Armadillos ; nor is there any tendency to form plexuses, such as are often met with in the Armadillos. In fact the venous system of Orycteropus is in its entirety more approaching that of other Eutherian Mammals. 3. On Decapod Crustacea from Christmas Island, collected by Dr. C. W. Andrews, F.R.S., F.Z.S. By W. T. Calman, D.Sc, F.Z.S.t [Received May 22, 1909.] (Plate LXXII.J) I. Introductory. This paper deals with the Decapoda collected by Dr. Andrews on his second visit to Christmas Island in 1908. The names of a few specimens obtained during his stay on the island in 1897-98 but not hitherto determined are also included in the list given below. Dr. Andrews has pointed out (P. Z. iS. 1900, p. 116) that " the^ shores of Christmas Island ar-e singularly unfavoui-able for the collection of marine animals," and practically all the marine * Am. Journ. Anat. vol. v. no. 2, 1906, p. 193, fig. 15. t Published by pei-missioii of the Trustees of the British Museum, X l!^or explauatiou of the Plate see p. 713.
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