16 ANIMAL PAEASITES. 



terminal joint as bearing three claws at its extremity ; a long one 

 arid two shorter. Wedl could not quite make out these extremi- 

 ties. If we make use of the assistance of varying illumination 

 of the preparation, we see, as I think, only a single hooked claw, 

 of a very delicate kind, projecting "from the centre of the foot. 

 On the sides of the anterior free margin of the foot we see a pair 

 of straight, acute processes, which are certainly not horny claws, 

 but only membranous projections of the extremity of the foot, 

 which probably 'even change their form in different move- 

 ments. With transmitted light the larger claw may be traced 

 distinctly as a lighter streak, a certain distance up into the 

 substance of the last joint of the foot, whilst the two apparent 

 lateral spines retain the colour of the mass of the foot itself. The 

 free-standing central claw apparently may be erected and somewhat 

 curled. Thus if we employ coloured oils (for example, Macassar 

 oil) in the examination, all the oil is sometimes displaced at this 

 spot during the movement of the foot, and a small round surface 

 is produced, which appears to adhere to the extremity of the foot 

 like a little sucking pit an illusion which has already frequently 

 occurred. 



We meet with the animal in several forms. 



First form. The abdomen is about three times as long as the 

 anterior part of the body ; the tail notched like a file. The 

 contents are finely granular, brown or blackish by transmitted 

 light ; we also see transparent, irregular, round, oval or quadran- 

 gular spots (fat-drops or epithelium). Some observers say they 

 have distinguished an oesophagus, intestine, and liver. This form 

 must certainly be one more approaching to maturity. 



Second form. The abdomen is considerably abreviated, until 

 at last it is scarcely larger than the cephalothorax, and when 

 regarded by itself forms a conical body, pointed towards the 

 caudal extremity, on which the rudiments of segments or trans- 

 verse rings may be distinguished. This form has always eight 

 legs. There is no doubt that it is the nearest to maturity. But 

 whether the appendage in question at last falls away entirely or 

 not, is at present still a matter of dispute. For my own part, it 

 appears to me improbable that it should be altogether thrown off. 

 Moreover, in one case, I found this form particularly plentiful, 

 whilst Simon mentions the first form as the most abundant ; 

 circumstances which probably vary according to the season, the 

 duration of the disorder, &c. 



