EAST KENT NATURAL HISTORY SOCIETY. 319 



plate at the back of the head. In many ova the large germinal 

 vesicle and its single spot or nucleus was plainly seen. As to 

 the males, they occur abundantly, and sexually mature, among 

 the little red specimens so numerous on pastures and trees or 

 shrubs. The spermatozoa are pale, quite liomogeneous, nearly 

 transparent, arcuate, sharp at one end, and blunt or truncate — 

 not clavate — at the other ; length l-185th of an inch, thickness 

 l-(ji00th. They disappear when treated with acetic acid, and 

 cannot be made to dry well ; in both these respects, as well as in 

 others, differing from the spermatozoa of insects and mammals. 

 The testis is a bunch of vesicles much like the ovary. 



Eggs. — Some of the large females, after a few days' confinement 

 in a tin box, deposited there many ova, feebly sticking together in 

 clumps often as large as the parent ticks. These eggs were 

 smooth, of a glistening chocolate colour, oval in shape, and each 

 about l-40th of an inch long and l-60th broad. Their shell 

 was composed of chitine ; its contents chiefly of corpuscles, some 

 globular, more of the same form as the shell, and presenting an 

 average length of l-500th and a breadth of l-727th of an inch ; 

 each distinct in outline, and all generally larger and more regular 

 in size than common yolk granules. The number of ova was so 

 great as to show the prodigious fecundity of these ticks, as, indeed, 

 is too well known to the flockmasters of this neighbourhood. 



Urinary Apparatus. — This is greatly developed, consisting of 

 two transparent tubes, easily recognisable by their opaque white 

 contents, having all the properties of guanine, and never showing 

 any trace of uric acid. In the more common sheep-tick, which 

 belongs to the hexapod insect-order Diptera, and is the Melophila 

 ovina of Nitzsch, and which was examined at the same time for 

 comparison, uric acid was always found. Thus these two 

 creatures, both living on the selfsame sheep, have their urinary 

 matter so essentially diifereut. And in the excrement of every 

 insect and spider examined the same diff'erence was found, 

 corresponding to the observations made on scorpions and 

 true spiders many years since by that eminent physiologist 

 John t)avy. And this important physiological character, now 

 extended to the Acarina, though not yet recognised in the books of 

 the zoological taxonomy, should fine a place there. The same holds 

 good of Argas (described as British in the ' Quart. Journ. Micro. 

 tSci.,' April, 1872), in which species the urinary granules are 

 opaque, white, smooth, shining, concentrically striated, more or 

 less globular or oval, with an average diameter of yoVctli of an 

 inch, and often two partly fused together. They present a truly 

 beautiful microscopic spectacle, especially when examined in 

 clusters within the urinary tubes. In Ixodes the urinary granules 

 are not so large and remarkable as in Argas. The urinary tubes 

 in both commence by a blind and sub-clavate extremity at the 

 fore part of the body, and proceed tortuously backwards to open 

 into the last portion of the intestine, where is a bilobed sac, — a 

 sort of urinary bladder, most distinct in Argas. 



