Description of a new species of the genus Callianassa Leach and of a species of the genus Alpheus Fabr., both from the Indian Archipelago

Callianassa (Callichirus) vigilax n. sp. Plate I, fig. 1—6. One female without eggs, collected in 1863 by Mr. Ludeking at Amboina. This new species is most closely related to Callianassa (Callichirus) armata A. M. - Edw. from the Fiji Islands, but may at first sight be distinguished by the shape of the abdomen, of the caudal fan and of the smaller cheliped, probably also by that of the larger, which, unfortunately, is wanting, like the flagella of the outer antennae. This specimen is 85 mm. long from tip of rostrum to end of telson and therefore belongs to the larger species of this genus; the carapace which is 22 mm. long, measures about one-fourth the whole length and one-third the length of the abdomen. Rostrum (Fig. 2) broadly triangular, acuminate, reaching to just beyond the middle of 1st antennular article and to the distal third part of the ophthalmopods, just beyond the eyes; upper surface of rostrum slightly convex transversely and longitudinally, obliquely directed downward in a lateral view, while the acute rostral point is directed horizontally forward. Like in Call. armata (A. Milne Edwards, Nouv. Archives du Muséum. Mém. 1870, T. VI, PI. I, fig. 1), the anterior margin of the carapace is armed, on either side of the rostrum, with a smaller acute spinule, just outside the eye-stalks; these spinules are directed obliquely inward and almost half as long as the rostrum, reaching as far as the distal margin of 1st antennal article. The gastric region (Fig. 1) which is twice as long as broad and strongly convex transversely, is separated anteriorly by a slight depression from