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Show 1902.] VARIATION IN THE NORWAY LOBSTER. 9 Mr. Bateson has, however, placed on record several cases of females of Astacus Jluviatilis with additional oviducal apertures, but their degree of frequency was not nearly so great as that of the abnormal spermatic apertures in Nephrops. After citing Desmarest's observation of a female Astacus with oviducal apertures on both the antepenultimate and penultimate legs, to each of which the oviducts branched, he describes several cases that he has himself observed. Among 583 female Astaci he records 23 which were abnormal in regard to the genital apertures, 17 having an opening on one of the fourth legs, one with an opening on each of the fourth legs, one with one opening on each of the fourth and fifth legs (in each case in addition to the normal openings), and four in which one of the normal openings was wanting. The oviducts in most cases gave off branches to the abnormal openings as in Desmarest's specimen. Mr. Bateson cites Dr. Benham's observation on a female crayfish which had a pair of supernumerary openings on the fifth legs but none on the fourth. Out of 714 males that Mr. Bateson examined, one was abnormal in having no spermatic aperture on the right side. No cases of additional spermatic apertures are recorded for Astacus. The above-described variations in Nephrops would appear to have some bearing on the supposed cases of hermaphroditism among the Astacidee. La Valette St. George has described a specimen of Astacus jluviatilis, in its external characters a male, but with what appeared to be a hermaphrodite gland. Bergendal in two papers has recorded his observations on females of Astacus ficviatilis in which the appendages of the first abdominal somite were modified as in the male ; and Faxon has cited other cases of partial or complete hermaphroditism. But it is only those cases where the evidence of hermaphroditism is supplied by the existence of apertures situated as in one sex, in animals which in many characters resemble the other sex, which specially concern the subject of this paper. In his ' Revision of the Astacida?' Faxon gives an account of a specimen of Cambarus propinquus, which appears to have been an undoubted female, for ovarian eggs were found on dissecting it. The external characters, including the condition of the appendages of the first and second abdominal somites, were also those of the female, with the exception of the position of the genital apertures, which were on the last pair of thoracic legs-i. e., in the position typical of the male. Lonnberg states that he believes he has seen rudimentary genital ducts passing to the third pair of thoracic legs in two specimens of Cambarus fallax, but owing to their state of preservation he is not positive. Yon Martens has long ago recorded the presence of additional apertures on the bases of the antepenultimate legs in certain male specimens of Cheraps preissii, Astacus pilimanus, and A. brasiliensis, the two latter of which are now included in Huxley's genus Parastacus. Von Ihering describes these apertures which occur in all the |
