OCR Text |
Show 18S8.] MORPHOLOGY OF SUPERNUMERARY PHALANGES. 495 EXPLANATION OF PLATE XXIII. Fig. 1. Longitudinal section through the generative segments of an immature example of Clitellio arenarius. cp, spermatheca ; t, testis;./', funnel of vas deferens; v.d, vas deferens; o, ovary; at, atrium ; ov, funnel of oviduct. 2. Longitudinal section through the oviducal funnel of a mature Clitellio arenarius. od, oviducal funnel, above is the body-wall; the epiderm in this (the clitellar) region consists of tall cells closely packed with granules. 3. Portion of a seminal sac of the same species, v, wall of the vescicle; bl, blood-vessel; s, developing spermatozoa. 4. A n egg-sac of the same worm, containing a single ovum ; bl, bloodvessel in wall of sac; the smaller black dots are nuclei of the connective or muscular tissue which forms the wall of the sac; the ovum is mature and full of yolk-spherules. 5. Transverse section through vas deferens of Clitellio arenarius ; this figure is drawn to the same scale as the following, with which it may be compared. 6. Transverse and longitudinal sections through vas deferens of Hemitubifex benedii. Drawn to the same scale as fig. 5. 7. Hemitubifex benedii, section to illustrate structure of atrium, &c. at, atrium ; v.d, vas deferens dilated above, near to its junction with atrium; pr, prostate. 8. Section through penis and penis-sheath of Hemitubifex benedii. V, penis with chitinous covering. 9. Section through penis and penis-sheath of the same species at a point further removed from the external orifice; the penis (p) is seen to be independent of the penis-sheath, which lies to the left-hand side. 3. Observations upon the Morphology and Genesis of Supernumerary Phalanges, with espeeial reference to those of tbe Amphibia. By G. B. HOWES, F.Z.S., F.L.S., Assist. Prof, of Zoology, Normal School of Science and B. School of Mines, S. Kensington, and A. M. DAVIES, Assoc. N.S.S. [Eeceived December 4, 1888.] (Plates XXIV. & XXV.) CONTENTS. I. INTRODUCTORY, p. 495. II. GENERAL AND ANATOMICAL, p. 49(5. III. HISTOLOGICAL AND DEVELOPMENTAL, p. 499. IV. INDIVIDUAL AND CLASSIFICATORY, p. 501. A. Phaneroglossa. B. Aglossa. C. Urodela. V. GENERAL CONSIDERATIONS, p. 506. VI. CONCLUSIONS, p. 509. VII. LIST OF MEMOIRS AND PAPERS REFERRED TO, p. 510. VIII. EXPLANATION OF THE PLATES, p. 511. I. INTRODUCTORY. There appeared in the second part of this volume a short paper (2) by Boulenger, in which the author verified and extended an earlier o4 |