Mr. A. Hancock on Vermiform Fossils. 443 



each other. But we have been unable to discover in these all 

 the characters of an ovum with the same distinctness as in the 

 preceding species, no doubt because they had not yet arrived at 

 their complete development. 



V. I have not witnessed the deposition of the ova in these 

 animals. It is very probable that they escape by the anus, or 

 by some neighbouring aperture. Thus, in the Stylonychice, I 

 have seen them collect in the posterior part of the body which 

 bears the anal orifice, and diminish gradually in number from 

 the first or second day after the copulation. It is a singular 

 thing, that about this period a round pale body begins to make 

 its appearance in the centre of the animal; this becomes con- 

 stricted about the middle, and reconstitutes the double nucleus 

 of Stylonychia. 



VI. The Infusoria are destitute of copulatory organs. In 

 most cases the copulation is effected by simple juxtaposition, 

 the two mouths establishing the sexual communication [Para- 

 mecium, Bursaria, Euplotes, Chilodon, Spirostomum). In the 

 Oxy trichina* the union is more intimate, and goes so far as to 

 constitute a true soldering of the two individuals for more than 

 two-thirds of their anterior part. Any one who had not wit- 

 nessed all the phases of this singular copulation, would be 

 unable to avoid regarding this state as a longitudinal division, 

 proceeding from behind forwards, in a single animal. But even, 

 if direct observation were wanting, the concomitant changes of 

 the internal organs, which are so characteristic, cannot leave 

 the least doubt as to the actual signification of this act. 



XLVIII. — Remarks on certain Vermiform Fossils found in the 

 Mountain Limestone Districts of the North of England. By 

 Albany Hancock*. 



[With six Plates.] 



In 1838, Mr. Dixon Dixon, of Unthank, presented to the 

 Newcastle Museum a few slabs of a fine-grained micaceous sand- 

 stone, which were procured from a quarry on Haltwhistle Com- 

 mon. These slabs exhibited on their surfaces peculiar elevated 

 and depressed markings, supposed at the time to be either the 

 fossil remains of worms, or casts of worm-tracks. 



Slabs bearing similar markings were likewise obtained by 

 Mr. Edward Wood, of Richmond, in 1850, from the same for- 

 mation in Wensleydale, Yorkshire, and were described by that 

 gentleman in two interesting communications published in the 



* Communicated by the Author, having been read at the Meeting of the 

 British Association held at Leeds, September 22, 1858. 



