[ 477 ] 



VII. The Internal Anatomy of Bdella. 

 £y A. D. Michael, V.P.L.S., F.Z.S., F.B.3I.S. 



(Plates 41-43.) 



Head lOth April 1896. 



Contents. 



Introductory Observations. 



Modes of Investigation 477 



Species used 478 



Position, Characters, and Subdivision of the 



Bdelliuaj .... 479 



Food of the Bdellinfe 480 



Former Eesearches 480 



The Trophi and Mouth-organs. 



Maxillary Lip and Exoskeleton of Rostrum. 482 



Palpi 483 



Mandibles 483 



Epipharynx 483 



Lingua 484 



The Alimentary Canal and Excretory Organ. 



Pharynx 485 



(Esophagus and Sucking-stomach 487 



Ventriculus 489 



Excretory Organ 489 



The Salivary Glands. 



General 492 



Tubular Gland 493 



Main common Duct 493 



Eeniform Gland 494 



Anterior Gland 494 



Pericibal Gland 495 



Azygous Gland 496 



The Brain and Nervous System. 



The Brain 497 



The Nerves 499 



The Eyes 503 



Page 

 The Eeproductive System. 

 The Male. 



General 503 



Testes 504 



Embedding-sacs 505 



Testicular Bridge 506 



Mucous Glands 507 



Glandular Antechambers 508 



Penial Canal 509 



Azygous Accessory Gland 511 



Laminated Gland 512 



Air-chambers 513 



External Labia 514 



Spermatozoa 514 



Course of the Spermatozoa to the Exterior 



and Functions of Organs 515 



The Female. 



General 516 



Ovary 516 



Oviduct 517 



Eeceptaculum aeminis 518 



External Labia 518 



The Eespiratory Organs 518 



The Dermal Glands 519 



The Endosternite 519 



The Musculature 52i) 



The External Cuticle 522 



Bibliography 523 



Explanation of the Plates 524 



Intkoductoky Observations. 



J. HIS paper contains the results of work extending over a period of more than three 

 years, and involving the careful dissection of several hundred specimens, besides the 

 preparation and study of numerous serial sections cut in all directions — i. e., sagittal, hori- 

 zontal, and transverse. The dissections have been made partly on sj)ecimens freshly killed , 



SECOND SERIES. — ZOOLOGY, VOL. VI. 65 



