162 Mr. J. E. Gray on some Species of Cephalophus. 



while the ova in uninjured females, after passing through that 

 organ, remained turgid and were hatched in due time, that they 

 now, from undergoing no intermediate process, fell from the ovi- 

 duct, shrivelled up readily and died. Whatever therefore might 

 be the real use or action of the bilobed vesicle, its very primary 

 importance was at all events determined by the death or life of 

 the ova, depending upon its being injured by puncturation or 

 not. 



The remainder of the paper was devoted to the prodigious fe- 

 cundity of Ixodes, the females of which, according to their indi- 

 vidual size, and the species whereunto they belong, give birth to 

 more than a thousand ova, being so employed, without intermis- 

 sion, from ten to thirty consecutive days. To deposit these ova, 

 the female when in a mature state of pregnancy detaches herself 

 from the animal upon whose blood she has lived as a parasite by 

 suction and falls to the ground ; the young, which are hatched 

 sooner or later according to the heat of the season, remain for 

 some time quietly congregated together, but at the first impulse 

 arising from want of food, they part company, and ascend the stalks 

 of herbs and shrubs to await the passing by of that animal upon 

 which instinct bids them subsist. They have then only six legs ; 

 but after the change has taken place, when the old rostrum and 

 integuments are left adhering to the skin of the animal upon which 

 they prey, they are then shown to be in an adult and perfect 

 state, that is, furnished with eight legs. The whole paper, rich in 

 facts, and of which the above is an abstract, was illustrated when 

 read by a wax model of the female Ixodes as seen, when largely 

 magnified, in the act of depositing her ova. It is to be hoped 

 that some such masterly observer and arachnologist as Mr. Black- 

 wall among our own countrymen may furnish us with additional 

 evidence relative to the singular facts here recorded. 



XIX. — Description of the Species of Cephalophus (H. Smith) in 

 the Collection of the British Museum. By J. E. Gray, Esq., 

 F.R.S. &c. 

 The determination of the species of Antelopes has for a long 

 time been considered one of the most difficult programs in zoo- 

 logy, and the Tufted Antelopes have perhaps been the least stu- 

 died of the group. Finding, when revising the nomenclatures of 

 the species of this genus in the British Museum collection, that 

 there were several which do not yet appear to have been de- 

 scribed, and that they appeared to have more prominent cha- 

 racters than have hitherto been given to them, I have ventured 

 to send you for publication in the ' Annals' the result of my re- 

 vision of the group. 



