In many modern Crustacea, the antennæ or antennules are modified as claspers, and it is barely possible that the curious double curvature of the antennules of Triarthrus indicates a function of this sort. The antennules of many specimens have the rather formal double curvature, turning inward at the outer ends, and retain this position of the frontal appendages, no matter what may be the condition of those on the body. Other specimens have the antennules variously displaced, indicating that they are quite flexible. It is conceivable that the individuals with rigid antennules are males, the others females. It is interesting to note that the antennules of _Ptychoparia permulta_ Walcott (1918, pl. 21, fig. 1) have the same recurved form. All the specimens of Neolenus, however, show very flexible antennas. Barrande and Salter laid great stress upon the "forme longue" and "forme large" as indicating male and female. This was based upon the supposition that the female of any animal would probably have a broader test than the male, a hypothesis which seems to be very little supported by fact. In practical application it was found that the apparent difference was so often due to the state of preservation or the confusion of two or more species, that for many years little reference has been made to this supposed sex difference. EGGS. In his classic work on the trilobites of Bohemia, Barrande described three kinds of spherical and one of capsule-shaped bodies which he considered to be the eggs of trilobites. After a review of the literature and a study of specimens in the collections of the Museum of Comparative Zoology, it can be said that none of these fossils has proved to be a trilobite egg, but that they may be plants. A full account of them will be published elsewhere. Walcott (1881) and Billings (1870) have described similar bodies within the tests of _Calymene_ and _Ceraurus_, but without showing positive evidence as to their nature. Methods Of Life. This is a subject upon which much can be inferred, but little proved. Without trying to cover all possibilities, it may be profitable to see what can be deduced from what is known of the structure of the external test, the internal anatomy, and the appendages. This can, to a certain extent, be controlled by what is inferred from the strata in which the specimens are found, the state of preservation, and the associated animals. (For other details, see the discussion of "Function of the Appendages" in Part I.) HABITS OF LOCOMOTION.