236 



SCIENCE-GOSSIP. 



which they are genetically related, and from which 

 they are the descendants. 



In many groups of the animal kingdom there are 

 known more extinct than living forms, while yet 

 other great groups are known only by fossil forms. 

 So great has been the evidence for evolution, for 

 descent with modification, that the late Professor 

 Huxley tells us that " The palaeontological dis- 

 coveries of the last decade are so completely in 

 accordance with the requirements of this hypothesis 

 that if it had not existed the palaeontologist would 

 have had to invent it."(i) 



Yet we may feel certain that but comparatively 

 few of the treasures locked up in the earth's crust 

 have been discovered. North America has yielded 

 to the patient work of Marsh, Cope, and others a 

 large number of new forms noticeable alike for 

 (1) Collected Essays, vol. iv., p. 44. 



their profusion and their remarkable characters. 

 Other regions are doing the same, and yet 

 others may be expected to do so when diligently 

 searched. 



The end is not yet : the future may open up 

 long vistas of thought and discovery, the effect of 

 which may perhaps be seen in such a reaction 

 between the present and the past as shall enable 

 the biologist of the future, with his knowledge of 

 organic forms and their succession, " to conclude 

 from a part to the whole, . . . from one or 

 two terms in such a succession to the whole 

 series, and thus to divine the existence of forms of 

 life, of which perhaps no trace remains, at epochs 

 of inconceivable remoteness in the past."(-) 



Royal College of Science, London, SJV. 



(-) Collected Essays, vol. iv., p. 45. 



PARASITE OF TORTOISE. 



T N April of last year I bought from a barrow-man 

 in the street a small Grecian tortoise, attached 

 to the hollow of the thigh of the hind leg of which 

 I found a parasite that for a long time defied my 

 utmost attempts to remove from its host. It was 

 nearly the size of a 



" 7% 



sheep-tick {Melapha- 

 gus ovinus), and its 

 head appeared to be 

 entirely embedded 

 in the flesh. Seeing 

 there was no chance 

 of capturing it alive 

 I applied a drop or 

 two of benzoline, 

 and when dead the 

 force necessary to 

 detach it by the aid 

 of a pair of forceps 

 was such as to tear 

 away a portion of 

 the skin of the tor- 

 toise. This I had 

 afterwards some 

 difficulty in removing 

 from the proboscis, 

 for fear of damaging 

 my specimen. 



Not having found a 

 record of this animal 



in any book I have seen I made drawings, using a 

 neutral tint reflector. These I enclose, and if you 

 can make any use of them I shall be pleased. 



The fleam-like lancets are admirable as instru- 

 ments for piercing the tough skin of the tortoise, 



Parasite of Tortoise. 



fl, drawn under 2" objective ; 6, head, i" objective ; c, lancets, 



J" objective ; rf, tarsus, |" objective. 



which, being accomplished, the double proboscis has 

 the faculty of extension, exactly as one would open 

 a pair of scissors. This fully explains the difficulty 

 of detachment. 



Turning from this diabolical -looking organ, one 

 is struck with the 

 extreme delicacy of 

 ? '^'^^ the tarsi, both in 



structure and attach- 

 ment. These appear 

 to be loosely pen- 

 dant, and can serve 

 no other purpose 

 than to help the 

 creature to drag 

 itself along the 

 c o ar s e 1 y-wrink 1 e d 

 surface of the skin of 

 its host. The anten- 

 nse, which have small 

 tufts of hair near their 

 extremiaes, lie back- 

 wards when the pro- 

 boscis has completed 

 its full insertion. 



The finding of a 

 parasite of this de- 

 scription upon such 

 an inhospitable 

 looking animal as 

 me a very interesting 

 glad to know more 

 Samuel Howarth. 



the tortoise 

 discovery, 

 about it. 



has been 

 I should 



26, Grange Crescent, Sheffield , 

 January, 1897. 



