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Show 84 MR. P. E. BEDDARD ON AN ANNELID [Feb. 5, being hollow ; so far at any rate " hypodermic impregnation" is improbable. The accompanying drawing (text-fig. 10) illustrates the form of the spermatophore, whose structure I have also investigated by transverse sections. Above the stalk it swells out into an oval cup, which is, roughly, of about the same length as the stalk. This narrows rapidly to form a short tube, which appears to be open at the free end. The thickness of the walls of this-the sperm-holding part of the spermatophore-are much thicker below and diminish gradually towards the free tubular extremity of the structure. This part of the spermatophore, as shown in the drawing, does not look as if continuous with the stalk ; a slight prolongation of the latter seems to embrace it. The deeply staining contents of the cup appear to be spermatozoa, but their condition of preservation is not sufficiently good to show histological details. Text-fig. 10. Npennatophore of Bothrioneuron iris in situ. Integumental vascular network.-A striking feature of the other two species of this genus is the existence of an integumental network of blood-capillaries. This was so easily to be seen in the examples of Bothrioneuron americanum which I examined, that I have some confidence in stating that a vascular integument is not to be found iu Bothrioneuron iris. I have examined ten or a dozen specimens in glycerine with and without treatment by potash, and I can find no trace of blood-capillaries in the skin. It occurred to me of course that the posterior end of |