OF A TETRACOTYLIFORM LARVA TO A HOLOSTOMUM SP. 387 



O. von Linstow farther states that he has always believed that 

 the laurer canal performed the functions of a vagina, and that 

 the anatomy of this new species Holostomum excisum showed the 

 impossibility of this, for in that species there are no signs of 

 a cirrus existing. The sperm is evolved at the posterior end of 

 the body (from the endodermic cells) which becomes a duct, and by 

 means of this duct it is conveyed to the uterus. Thus if in this 

 species the laurer canal possesses the function of a vagina, then, 

 under similar circumstances, it is applicable to other species of 

 Distomidae. 



Von Linstow illustrates his article with three figures. All 

 these figures are sectional, and valuable anatomically, but they 

 by no means show the natural beauty of this Holostomum. 



I took this tine worm in the first instance from amongst the 

 contents of the alimentary tract of a teal {Anas creca, Linn.) 

 daring the winter of 1906 and 1907. I prepared, stained, and 

 mounted my specimens, but did not make any sections. I also 

 studied the species and prepared a paper for insertion in the 

 Qaekett Journal. I was unaware until von Linstow sent me his 

 published work that he had already described and figured the 

 species. I have consequently withdrawn the proposed paper, 

 and have substituted the conclusions of von Linstow in place of 

 my own. Although, of course, disappointing, it is some satisfac- 

 tion to know that in the main one's own observations coincide 

 with those of a previous investigator. 



Part II. 



In the Jenaischen Zeitschrift fur Naturwissenschaft, 28 Bd., N.F. 

 21, Taf. 22, Figs. 1-S (Jena, 1894), O. von Linstow contributes an 

 article on " Tetracotyla typica, Dies.," which I take it he considers 

 to be the larval stage of a Holostomum which he found in an 

 encysted form in the liver of Limnaea stagnalis taken from a 

 lake in the neighbourhood of Gottingen. In this article he quotes 

 and explains the views of various authors who have written on 

 the larval or cystic forms of Trematoda, viz. Creplin, Steenstrup, 

 Schomburgk, De Filippi, Pagenstecher (see Cobbold's Parasites 

 of Man and Animals), Diesing, and Ercolani. He also 

 gives a detailed account of the various slugs which he found 

 acting as host to this cyst. He lucidly describes the contour of 



