File:Image from page 521 of "On the anatomy of vertebrates (electronic resource)" (1866) (14755596345).jpg

Identifier: b20416039_001 Title: On the anatomy of vertebrates [electronic resource] Year: 1866 (1860s) Authors: Owen, Richard, 1804-1892 Subjects: Anatomy, Comparative Vertebrates Fishes Reptiles Mammals Birds Publisher: London : Longmans, Green Contributing Library: Wellcome Library Digitizing Sponsor: Wellcome Library

View Book Page: Book Viewer About This Book: Catalog Entry View All Images: All Images From Book

Click here to view book online to see this illustration in context in a browseable online version of this book.

Text Appearing Before Image: any fissuresin the skin, ib. k, as those by which they enterfrom the pharynx, ib./: these are called fixedgills, and the species possessing them are cha-racterised as (pisces branchiis fixis. In theTeleostomi = Osseous, Plectognathic, Lopho-branchiate, Ganoid, and Holocephalous fishes,the outer border of the supporting branchialarch is unattached to the skin, and plays freelybackward and forward, with its gill-surfaces,in a common gill-cavity which has a singleoutlet, usually in the form of a vertical fissure:the species with this structure are called e pisces branchiisliberis. In the Myxine the outlets of the six lateral branchial sacs, fig.315, m, on each side are produced into short tubes, which openinto a longitudinal canal, k, directed backward, and discharging 1 cxlv. p. 258. Prof. Milne Edwards has exemplified this homology by the sub-joined formula:— Osseous Fishes b . ac. b 1 b2 b3 b4 b .TiT b~TT TtT T~zT. Plagiostomous Pishes -11—>—Is—.—Is—.—- Bl b2 b2 b4 b5

Text Appearing After Image: Branchial organs,Myxine GILLS OF FISHES. 477 316 the branchial stream by an orifice, k, near the middle line of theventral surface: between the two outlets of these lateral longi-tudinal canals, but nearer the left one, is a third larger opening,i, which communicates by a short duct with the end of the longoesophagus, /, and admits the water, which passes from that tubeby the lateral orifices, f, leading into the branchial sacs. This isthe first step in developement beyond that simpler condition whichprevails in the Lancelet, where the whole parietes of a muchdilated oesophagus, fig. 169, rr, are organised for respiration ; andbesides the pharyngeal opening, ph, the sac communicates by ashort and wide ductus oesophago-cutaneus, ib. od, with theexternal surface, and also with the peritoneal cavity. Thecommon respiratory surface of the oesophagus is ciliated in theLancelet. The sacs developed from the oesophagus, and speciallyset apart for respiration in the Myxinoids, have a highly vas

Note About Images