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Show 1892.] NEW SPECIES OF EARTHWORMS. 149 indented by a septum, so as to lie partially in two somites ; the dorsal vessel is doubled in three somites only. * Remarks on the genus Kynotus, Michaelsen. Dr. Michaelsen has recently described two species of this new genus which present certain anatomical features that are so unusual as to deserve a reconsideration. Kynotus madagascariensis1 and K. longus2 both come from Madagascar. The description of them is very incomplete, both as regards external and internal anatomy, owing to the bad condition of the specimens. These were not mature, and no clitellum was present. The chcetce are absent in the anterior part of the body in the first twenty-six " segments " (Mich.), so that the correct interpretation of these external markings is a matter of considerable uncertainty ; nor does the position of the nephridiopores aid us in determining the value of these surface-markings, as the author does not state where these pores commence ; they are in line with the inner (ventral) couples of chaetae in those segments where these are present ; in the anterior twenty-six " segments," however, they are on alternate rings. The grooves separating the rings are stated to be well marked, and in K. longus each " segment" is biannulated. Thus, from external characters, there is nothing to guide us to a correct enumeration of the true somites. Internally, the septa are, in most worms, of use, to some extent at least, for the determination of somites, and the position of the sperm-sacs and ovaries is so generally constant that these organs are frequently of considerable help in confirming any otherwise doubtful determination of somites. But according to Michaelsen's view of the anatomy of these two worms, the first septum lies between "segments" 7 and 8 ; and the ninth septum between " segments " 23 and 24 ; so that two " segments " (instead of a single one as is usually the case) occur between every two successive septa. Behind the ninth septum, however, the condition of things usual in Oligochceta obtains. But although there are two "segments," yet there is only one pair of nephridia. Michaelsen gives no information as to the condition of the vascular or nervous system, which might have aided us in solving the difficulty as to the value of his " segments." When I read his description of these worms I was reminded of my own difficulty in determining the value of the external rings and the limits of the somites in Microchceta rappi, and this difficulty still further impressed itself on me when I examined the specimens of the two new species of the genus described in the present paper ; at first I reckoned as somites the markings which I have above termed " annuli." Now, when we consider the very abnormal condition of things 1 Michaelsen, Arch. f. Naturgesch. 1891. * Michaelsen, Jahrb. d. Hamburg, wiss. Anstalt, ix. 1891. |
