326 ENTOZOA. 



without relation to sex, the aloe being strongly pronounced and 

 broad in some, whilst in others they are attenuated and incon- 

 spicuous. The stress, therefore, which Belhngham and others lay 

 upon these appendages, in view of determining specific differentia- 

 tions, is utterly valueless, at least, in so far as mere size and con- 

 spicuity are concerned ; but when variations of outhne — constant, 

 within certain hmits — are found associated with other peculiarities, 

 either of structure or habit, then the question of specificity is 

 fairly raised. In the present case I entertain no shadow of doubt 

 as to the identity of Bellingham's Ascaris alata with Dr. Pickell's 

 nematode, " similar to the supposed Ascaris felis," and with the 

 round-worms contributed by Mr. Scattergood. They are all 

 examples of the ordinary Ascaris mystax of the cat, a species 

 with which helminthologists are perfectly familiar. 



In executing the magnified views which I have given at page 325 

 (6, 8, 9, 10), I was careful to employ a camera to ensure accuracy; 

 but this plan was evidently not pursued in the amphfied represen- 

 tations shown by Drs. Bellingham and Pickells. I mention this, 

 not to cast a slur upon their extremely interesting communica- 

 tions, but to caution systematists against relying upon comparative 

 differences of outline, when these would not have been so strongly 

 indicated if the same method had been pursued by these authors in 

 delineating the ascarides which came under their observation. On 

 this subject I might say much more, but I have now fairly proved 

 that the Ascaris mystax should henceforth be numbered among the 

 human Entozoa.* 



Structure and Development. — Into the anatomy of this worm it 

 is quite unnecessary to enter, as, in the main, it closely corres- 

 ponds with that of the larger species already described ; bat as we 



* The foregoing remarks form the basis of a communication first published in the 

 pages of the " Lancet " for January 10, 1863, and subsequently reprinted in the " Dublin 

 Medical Press," for February of the same year. I had also previously advocated similar 

 views in my paper communicated to the British Association in September 1862, and also, 

 afterwards, at the Zoological Society. See " Proceedings of Zoological Society " for 

 November 20, 1862.-T. S. C. 



