[ 47 ] 



II. Oil some JPolnts ill the Visceral Anatomy of the Characiiiidce, with an Enquiri/ into the 

 llelations of the Ductus Tneumaticits in the Fhysostomi generaUy. By Walter 

 S. PbOWNTllEE, B.Sc., F.L.S. 



(Plates 3 & 4.) 



Head 5tli March. 1903. 



Synopsis. 



Page 



Introductory 47 



The Alimentary Canal and its Appendages (iucluding the Air-Bladder) 52 



The Ductus Pneumaticus and its relations in the Physostomi generally 63 



The Ovaries and certain other Structures 73 



Ifote on a Parasite found in one of the Characinidw 7G 



Summary and Conclusions 77 



List of the chief "Works consulted iu the course of the Invest iaration 79 



IXTKODrCTORT. 



IHE notes here embodied represent an investigation, begun two years ago, in the course 

 oC which I have had under examination a considerable number of spirit-specimens and 

 skeletons, representing some 55 species and 33 genera of the Characiuidoe. Access to 

 these has been permitted me by G. A. Boulenger, Esq., E.ll.S., of the British Museum 

 of Natural History, of whose sympathetic assistance I cannot speak too gratefully. Eor 

 jDxxrposes of comparison I have also had under examination certain Cyprinoids, Siluroids, 

 Gymnotids, and other Physostomes, together with Polypterus, Protopterus, Acipenser, 

 Amia, and Lepidosteus, for the tAvo latter of Avhich I am indebted to the kindness of 

 Professor Bashford Dean, of Columbia University, New York. The investigation owes its 

 initiation to Professor G. B. Howes, E.ll.S., wliose encouragement and helpful criticism 

 hare been of the greatest value to me throughout. 



Eurther, I gladly avail myself of this opportunity of expressing my indebtedness to 

 other friends for assistance rendered : to C. E. Stansfield, Esq., M.A., and to Fraiilein 

 Stoy, for facilitating at various times the labour inA'olved in searching the literature of 

 the subject; and to the llcv. T. R. B. Stebbing, E.ll.S., for kindly identifying for me a 

 rare parasitical crustacean mentioned in the text. The starting-point of my work has 

 been Sagemehl's masterly papers on the skidl of the Characinida?, and on the accessory 

 branchial organ of Citharinus, published in the ' Morphologisches .Tahrbuch ' for 1885 

 and for 18S0-7. I have also matle large use of Boulenger's * Les Poissons du Bassin du 

 Congo ' and • Materiaux pour la Faune du Congo ' ; of G anther's ' Catalogue of the Fishes 

 in the British Museum,' vol. v.; of Cuvicr and Yalenciennes's ' llistoirc NaturelJe des 

 Poissons,' vols. xix. and xxii. ; of Stannius's 'Anatomic dor Wirbi'lthiere,' and of several 

 other works. 



SECOND SERIES. — ZOOLOGY, VOL. IX. 8 



