384 Transactions of the Society. 



XXI Is not the Botiferous Oenus Pedalion of Hudson synony- 

 mous with Hexarthra ofLudidg Schmarda? 

 By JuLiEN Deby, F.K.M.S. 



(BeadSth January, 1879.) 



Looking lately through the plates iilustratino; Ludwig Schmarda's 

 ' Zur Natnrgeschichte ^gyptens ' (Yienna, 1854), I fell accidentally 

 upon the figure of an extraordinary rotifer which reminded me 

 forcibly of Dr. Hudson's Pedalion. From the imperfect figure, 

 plate iii. fig. 1, of Schmarda's work, I referred to the text for 

 fuller details, which are to he found on p. 15. We see there that 

 the rotifer called Hexarthra i^lyptera was discovered by Schmarda 

 on the 19th of March, 1853, in a small pool near the ruins of El 

 Kab, in Egypt. The water was brackish to the taste, and the 

 animal lived in it in shoals or " swarms." Although at the first 

 aspect Schmarda thought he had to do with some small crustacean, 

 he soon discovered the true position of his animal in the family 

 Hydatinea. 



His examination, although insufficient for clearly establishing 

 identity of generic characters between Hexarthra and Pedalion, is, 

 however, sufficiently detailed to allow of great doubts being ex- 

 pressed as to the right of existence of the latter name. The 

 differences between Hudson's and Schmarda's descriptions reside 

 principally in the incompleteness of the details given by the latter, 

 and are consequently differences of omission rather than anything 

 else. Schmarda's work being rather difficult of access, I have 

 translated therefrom his description in full of Hexarthra j[)olyptera, 

 which I reproduce for the sake of comparison with Dr. Hudson's 

 careful and elaborate papers, published in ' Month. Micr. Journ.,' 

 vol. vii., 1871, p. 121 ; in ' Quart. Journ. Micr. Sc.,' vol. xii., 1872, 

 p. 333 ; and in ' Month. Micr. Journ.,' vol. viii., 1872, p. 209 :— 



" The body is transparent, colourless, and represents a blunt cone, 

 at the broad end of which are situated the rotary organs. These 

 last are large, with numerous long cilia, and are so attached as to 

 form a right and a left group. Two globular red eyes are seen in 

 the middle of the forehead, not far asunder. The digestive appa- 

 ratus is very distinct ; an undulating (flimmernde) slit (mundspalte) 

 leads into a conical oesophagus, moved by four muscles, and carrying 

 two semicircular jaws, each of which is furnished with seven teeth. 

 The build of the masticating apparatus has some resemblance to 

 that of Triarthra. The stomach is short, but rather broad, and leads 

 into a cylindrical, many times constricted intestine, which narrows 

 at its lower end. The absorption of carmine was easily obtained. 

 At the upper portion of the intestine two pancreatic glands, which 

 are divided into two lobes, are seen to open. The organs of respira- 



