324 EVENINGS AT THE MICROSCOPE 



most exquisite beauty. The material has all the transpar- 

 ency and sparkling brilliance of flint-glass, while the ele- 

 gantly-shaped pins, the perfect symmetry of the prismatic 

 bases, the arch which is lightly thrown across their cavity, 

 the minute teeth of the tips locking accurately into each 

 other, and the oval cavities in the whole structure set in 

 regular rows, and reflecting the light from thousands of 

 points, constitute a spectacle which cannot fail to elicit 

 your admiration. 



P. globifera is formed on the same model as P. tri- 

 phylla, but is more globose, and each piece appears to have 

 a deep cleft at the point, which does not extend to the 

 interior side, where a thick ridge runs down from the 

 point to the base. At the summit of this ridge, in each 

 of the three divisions, there is set a strong acute spine, 

 directly horizontally inward, so that the three cross each 

 other when the blades close, which they do energetically 

 a formidable apparatus of prehension! The stem is 

 much more slender than in P. triphylla, and the height 

 of the head of one of average size is only ^d of an inch. 

 It is peculiar also in being slender throughout, and in 

 having the knobbed calcareous stalk extending up to the 

 head, which appears to work on it. In each of the other 

 sorts the stalk extends only through a part of the distance, 

 above which the investing fleshy neck becomes wider and 

 empty. 



But the internal structure is not quite the same as in 

 the others. The main portion of the head is composed of 

 gelatinous flesh; the calcareous support being reduced to 

 that ridge which runs up the interior side of the blade. 

 This is somewhat bottle-shaped, with a bulbous base, and 

 a long slender neck, with two edges on the inner face, 



