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Show 1885.] NEW-ZEALAND EARTHWORMS. 831 structure of the diverticula, which, as already mentioned, are extremely small, or to compare their structure with that of the main pouch ; but I am able to state, as a fact, that the spermatozoa were contained within the diverticula and not in the pouch. The foregoing considerations appear to me to indicate that the diverticula of the copulatory pouches are not merely "diverticula," serving to increase the storage room, but perform some definite function in relation to the spermatozoa, which function is not shared in by the copulatory pouch itself; the very general prevalence of diverticula to the copulatory pouch among Earthworms is an additional piece of evidence that these structures have some importance per se. In some species of Perichata these supplementary pouches attain to an extraordinary degree of complication, and are quite divorced from the main copulatory pouch, opening on to the exterior by separate orifices. In Microchata the copulatory pouch itself has apparently disappearedl, and only the supplementary pouches remain. Microchata is therefore at one end of the series, and Lumbricus, where there are no diverticula at all, at the other. I have searched the literature of the subject in order to find out how far the statement that I have just made with regard to the copulatory pouches are in harmony with the observations of other writers. Perrier mentions that in Urochata he never found spermatozoa in the copulatory pouches ; but the observation is not of much value, as Perrier himself points out, since the examples of the worm were, without exception, in a condition of incomplete maturity. I can find no other positive statement except in Huxley's ' Anatomy of Invertebrated Animals,' where it is mentioned that the pouches are filled with spermatozoa when copulation takes place. It is possible that this does actually take place even in Acanthodrilus dissimilis, and that the speimatozoa are rapidly got rid of, and transferred to the diverticula, where they are compacted into masses. This is at any rate in accordance with the facts which I have been able to describe. Dr. Horst2 mentions that in Perichata sumatrana the diverticula of the copulatory pouches contained "an orange-coloured substance which, highly magnified, appeared to be a mass of spermatozoa." In briefly running over the specific characters of the third species treated of in the present paper, viz. A. multiporus, I mentioned that the copulatory pouches appeared to be like those of Lumbricus, simple spherical sacs without diverticula. This statement requires some correction ; on making a series of transverse sections through the copulatory pouch and the body-wall in its immediate neighbourhood, I detected a number of minute diverticula opening into the duct of the copulatory pouch just before its external aperture, and imbedded in the muscular layers of the body-wall. The diverticula, as in the other instances, contained abundant spermatozoa, which were entirely absent from the interior of the copulatory pouch itself; the latter contained a granular mass which appeared to be the 1 Proc. Roy. Soc. no. 238, 1885, p. 462. 2 Notes from Leyden Museum, vol. v. p. 190. 54* |