PROGRESS OF MICROSCOPICAL SCIENCE. 107 



the direction of the pinna ranges from a slight but decided anteversion, 

 to an almost complete retroversion. 



In the seven pigs of another litter * averaging ' 040, in length, 

 the lids range from folds covering slightly the upper and lower 

 margins of the ball, to complete closure. The sizes and degrees of 

 closure do not exactly coincide. It would be interesting in both these 

 cases to know the relative position of the individuals in the mother's 

 uterine cornua ; but these facts indicate the need of far more extended 

 comparisons than have been made. 



I have also observed some striking changes in the form of the 

 nostril in foetal pigs ; it is in its earliest condition a notch, whose 

 lower margins then come together forming a hole ; this elongates 

 laterally and is indented above so as to become more and more cres- 

 centic ; but at or before birth the circular form is regained and 

 retained through life. 



To icJiat Group is Peripatus related ? — In the very last number of 

 the ' Proceedings of the Eoyal Society ' is an admirable paper on this 

 subject by Mr. H. N. Moseley, M. A., of the ' Challenger ' expedition. 

 Mr. Moseley enters into details concerning certain points in anatomy 

 which aj)pear to have been wrongly or imperfectly described before. 

 Thus he describes fully the Intestinal, Tracheal, and Eeproductive 

 systems, and gives an outlinear sketch of the development. Then he 

 goes on to say that " in the present state of our knowledge concerning 

 the structure of Peripatus, the most remarkable fact in its structure is 

 the wide divarication of the ventral nerve cords. The fact was con- 

 sidered remarkable, and dwelt ujion in all accounts of Peripatus 

 before the existence of trachete in the animal was kno^oi, and when 

 it was thought to be hermaphrodite, but it is doubly remarkable now. 

 The fact shuts off at once all idea of Peripatus being a degenerate 

 Myriopod, the evidence against which possibility is overwhelming. 

 The bilateral symmetry and duplicity of the organs of the body, the 

 absence of striation in the muscles, of periodical moults of the larval 

 skin in development, and of any trace of a primitive three-legged 

 condition, taken in conjunction with the divarication of the nerve 

 cords, are cor elusive. The parts of the mouth are not to be regarded 

 as degraded to any great degree ; and homologies for some of them, 

 at least, may perhaps be found amongst the higher Annelids. The 

 structure of the skin is not at all unlike that in some worms, especially 

 in its chitinous epidermic layer, which occasionally strips off in large 

 pieces as a thin transparent pellicle. The many points of resemblance 

 of Peripatus to Annelids need not be dwelt upon ; they led to its 

 former placing in classification ; but it is difficult to understand how 

 the very unannelid-like structure of the foot-claws did not lead 

 others, beside De Quatrefages, to draw a line between Peripatus 

 and the Annelids. In being unisexual, Peripatus is like the higher 

 Annelids, as well as the whole of the higher Tracheata. To Insects 

 Peripatus shows affinities in the form of the spermatozoa, and the 

 elaboration, structure, and bilateral symmetry of the generative organs, 



* Marked 303 to 309 iu the same catalogue. 

 VOL. XII. I 



