1890.] VISCERAL ANATOMY OF THE AUSTRALIAN TORPEDO. 66!) 



4. On the Visceral Anatomy of the Australian Torpedo 

 {Hypnos subidyrum), with especial reference to the 

 Suspension of the Vertebrate Alimentary Canal. By 

 G. B. Howes, F.Z.S., F.L.S., Assist. Professor of Zoo- 

 logy, R. College of Science, S. Kensington. 



(From the Huxley Research Laboratory.) • 



[Eeceired December 2, 1890.] 

 (Plate LVII.) 



The Australian Torpedo, Hypnos subnigrum, was first described 

 by A. Dumeril ' from two specimens, deposited in the Paris Museum 

 by Mons. J. Verreaus. Its skeleton has been dealt with by 

 Haswell ^ and has been shown to be in some respects exceptional 

 and peculiar, while its electrical organs have recently been written 

 about by G. Fritsch, in the second volume of his ' Die elektrischen 

 Fische'^ During the Fisheries Exhibition held at South Ken- 

 sington in 1883, Mr. Ramsay, Curator of the Sydney Museum, 

 brought some specimens of this fish to Europe ; three of them are 

 now in the Museum of Natural History, two (a c? and a $ ) in ray 

 teaching collection at South Kensington, For the gift of these 

 animals, zoologists at home owe Mr. Ramsay and the authorities of 

 his Museum a debt of gratitude. 



On laying open the post-pericardiac body-cavity of this fish, the 

 alimentary tract is seen to be disposed in the manner of an inverted S, 

 as is the case in all the Ichthyopsida and the lower Amniota. That 

 is to say— a line (a, /3 of Plate LVII. fig. 1) drawn parallel with the 

 long axis of the body would bisect the oesophagus and cloaca, 

 together with a more or less considerable portion of the large 

 intestine, and leave tlie stomach {cd., py.) to the left and the small 

 intestine (i.s.) to the right of the animal. 



The hver {ftp.), which is two-lobed'', lies, as usual, ventrad of the 

 stomacli on the left side, and to the right and dorsad of the small 

 (valved) intestine {i.s.") on the opposite one. Its gall-cyst {c.b., 

 so called gall-bladder) is exceptionally spacious and lies disposed 

 in a notch of the right lobe. Tliis right liver-lobe is much the 

 larger of the two, and it extends inwards in tliis fish to an unusual 

 degree, reaching almost to the middle line and forming (as seen from 

 beneath) a kind of bed upon which the valved intestine lies. The 

 latter, which, unlike that ot most Chondrichthyes, bears no well-marked 

 external furrows denoting the course of its contained valve, has the 

 customary proportions and relationships, but that its duodenal 

 segment (or Bursa Entiana, i.s.') is more tubular than is usually 

 the case, Lcemargus excepted \ and is marked off from the stomach 



' Eey. et Mag. de Zoologie, 1852, no. 5, p. 277. 

 ^ Proc. Linn. Soe. N. S. W. vol. ix. part 1. 

 ^ Leipzig, 1890. 



■* As in Trygon, Urolophm, and Myliobatis, Haswell, Proc. Linn. Soc. N.S.W. 

 vol. iii. (ser. 2), p. 1716. 

 5 Cf. Turner, Jouru. Anat. & Phys. vol. vii. p. 233 (1873), 

 Proc. Zool. Soc— 1890, No. XLV. 45 



