THE MICROSCOPE. 825 



teeth of the median band single, wedge-shaped, with points slightly 

 recurved ; teeth of the lateral bands, five on each side, with 

 strongly recurved points, the central the most so. The outermost 

 bands are called " pleurae," and having numerous teeth these are 

 said to be indefinite. This arrangement is readily expressed by the 

 formula, 00.5.1.5.00. As these parts are situated on the floor of 

 the mouth, they cannot be correctly designated '• palate,"' that 

 being the roof of the mouth. Nor do I see any necessity for the 

 new term " Odontophore " (tooth-bearer), the part being, in strict 

 homology, the tongue, and fairly comparable to the tongue, with 

 recurved points (cornified papillae) of the ox or the cat. 



Pediculus Capitis (PI. XIII. , Fig. 4). — The objects on this 

 slide are small because they are youngsters, little more than just 

 hatched out of the egg. They show, in an interesting way, the 

 disproportion between limbs and body which we often note as 

 giving a grotesque appearance to young animals of a higher type — 

 calf, colt, puppy, or what not. Occasionally, examples may be met 

 with just previously to moulting, where the soft parts are slightly 

 withdrawn from the outer integument, previous to rupture of the 

 latter, and exuviation. They then look like a louse within a louse. 



Larva of Lace-wing Fly (PL XIII., Figs. 1-3). — The trumpet- 

 shaped sucker (Fig. 2), terminating each limb between the claws, 

 is only a special modification of a similar part so universally 

 present in bees, ants, wasps, and the like, that it may be termed 

 the " Hymenopterous " type of foot. Certain Neuroptera, as the 

 Lace-wing fly, in its natural state, present good examples of a 

 similar form. 



Injected Human Lung (PI. XII., Fig. i). — In specimens such as 

 these, it must always be remembered that we are viewing capillar- 

 ies ; minute vessels, intermediate in position between veins, carry- 

 ing exhausted, and arteries bearing renovated blood. It may be 

 doubted if any injections with two colours, as here seen, express 

 correctly the anatomical facts of the case. 



