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V. On the Intestinal Spiral Valve in the genus Raia. By 'T. Jerrury Parker, B.Sc. 
Assoc. RSM, Lecturer on Biology in Bedford College, London, and Demonstrator 
in the Royal School of Mines. (Communicated by Prof. T. H. Huxtey, F.R.S.) 
Received November 7th, 1879.—Read December 16th, 1879. 
[Puates X. & XI.] 
ConTENTs. 
HE mUMEROOMCLOLY sicie cich ashe eslstos aves acters §1 10. Concluding remarks on spiral valve of 
2. Method of examination .............. § 2 UO Rese Aalte u, opdloneschvsepes ors A sinteereyune § 13 
3. Generic description of intestine of Raia.. § 3 11. Spiral valve of Scylliwm..............- § 14 
4, Table of constant and inconstant features JD 58 Waaraet LVOULUTIUUS ite 1.2, Seance a Ras § 15 
in spiral valve of Raia .............. $4 is eager 5). 33 CCSINACION. ce, 5 ahora $ 16 
5. Detailed description of spiral valve of Raia iY ena as a Crameana ise eee ata § 17 
§§ 5, 6, & 8 15. Scroll valve of Zygana .............. § 18 
6. Definition of the four types of spiral valve § 7 16. Spiral valve of Lepidosiren and Cera- 
7. Variations in absorbing surface of spiral COMUS (ag Basssopel eS. ccoyaio/apepseLayei erate ole § 19 
PVR CE Me yastie oie cuaye deocereys loi = axayo §§ 9 & 10 17. Spiral valve of Petromyzon .......... § 20 
8. Obstruction to passage of food offered by 18. Concluding remarks, and table showing 
the various forms of valve .......... § 11 relations of spiral and scroll valves $§ 21 & 22 
9. Character of mucous membrane of spiral 
TELS Gets Die heieeene 6 OE IRCCS § 12 
T have not judged it necessary to give a special abstract of the paper, as all the results of my observations 
are to be found in a condensed form in §$ 4, 6, 10, 13, and 21. 
§ 1. For the last few years I have had the opportunity of examining a large number 
of intestines of various species of Raia, and have been greatly struck with the astonish- 
ing amount of variability exhibited by the spiral valve—a variability most surprising 
when one considers the great physiological importance of the structure in question, 
and the extent of the probable lapse of time since it first came into existence. 
The best accounts of the spiral valve are to be found in the works of Claude 
Perrault ', Miiller?, and Duméril*, the two latter giving a general description of the 
valve, with the main differences it presents in the chief genera of Elasmobranchs, while 
Perrault has an excellent figure and description of the very typical form of valve dis- 
covered by him in the “ Renard marin.” I have been able to find none but the most 
general description of the valve of Raia; and the only figure of it I have met with is 
that in Monro’s ‘Structure and Physiology of Fishes,’ where, being drawn in its flabby 
fresh condition, it is impossible to get any correct idea of its form and relations. 
1 «Mém, pour servir 4 Vhist. nat. des Animaux,’ 1671. (Republished 1736.) 
* Anatomie der Myxinoiden. 3 Tchthyologie Générale. 
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