DESCRIPTIONS OF NEW SPECIES. 135 



situation the rest of the body occupies. The ventricles and vessels 

 have been split up, and unless the spirit has altered appearances 

 very much, you will have no difficulty in finding the parasites. 

 Perhaps before attempting their removal it would be well to soak 

 the heart in some solution of about the specific gravity of blood. I 

 find urine answer v^ery well for this purpose ; it restores the pro- 

 portions lost by exosmosis. 



" Hcematozoa of Corvus torquatus. — About one third of the 

 crows I have examined contained two kinds of blood worms. 

 These two kinds are quite unlike each other, but whether they 

 are of distinct species or only different stages of the same I am not 

 prepared to say. Of the two kinds the larger measures from 

 -rio" to yi/ by ^^^-^', the smaller ^y by ^/. The former is 

 very active and has a lashing, free, vigorous style of movement ; 

 the latter is languid and has a slow, wriggling, worm-like motion. 

 The oral movements in both kinds are very distinct, and when it is 

 open four papillse can be distinctly seen surrounding the mouth. In 

 the larger species a bright line extends backwards from the mouth 

 into the body suggesting an oesophagus. The tail of the larger 

 kind is gradually tapered down and pointed, and the general 

 contour of the body and habits of this embryo resemble very 

 closely those of the embryo of Filaria immitis. The tail of the 

 smaller kind tapers but slightly and is abruptly truncated, and by 

 careful focussing one can in most specimens detect a thin skin ex- 

 tending like a loose bag or hood from the head. The truncated 

 tailed and hooded embryos die very soon after being placed on the 

 slide, but their companions I have seen alive and active in an oiled 

 slide ninety-six hours after their removal from the host. Though 

 the proportion of these two kinds of embryos varies considerably in 

 different birds, yet where one is found the other is sure to be present 

 also. 



" Parents are sometimes found in the right ventricle, but most 

 commonly in the pulmonary artery and its branches. The best way 

 to find them is to open the pericardium, and after dragging the 

 heart well up with a hook transfixing its apex, scrape with a blunt 

 knife as much as possible of the soft lung tissue from the pulmonary 

 arteries and then divide them deep in the lung. They can then be 

 easily split up or divided at intervals and the worms expressed. 

 Those I send you were thus obtained, and are the produce of one 

 bird. 



