434 UTRICULAEIA MONTANA. Chap. XVIIL 



and rubbish ; so that the curvature of the antennae is 

 a serviceable character. There are no bristles on the 

 outside of the collar or peristome, as in the foregoing- 

 species. 



The valve is small and steeply inclined, with its free 

 posterior edge abutting against a semicircular, deeply- 

 depending collar. It is moderately transparent, and 

 bears two pairs of short stiff bristles, in the same 

 position as in the other species. The presence of these 

 four bristles, in contrast with the absence of those on 

 the antennae and collar, indicates that they are of 

 functional importance, namely, as I believe, to prevent 

 too large animals forcing an entrance through the 

 valve. The many glands of diverse shapes attached 

 to the valve and round the collar in the previous 

 species are here absent, with the exception of about 

 a dozen of the two-armed or transversely elongated 

 kind, which are seated near the borders of the valve, 

 and are mounted on very short footstalks. These 

 glands are only the -^-^^ of an inch ('019 mm.) in 

 length ; though so small, they act as absorbents. 

 The collar is thick, stiff, and almost semi-circular ; it 

 is formed of the same peculiar brownish tissue as in 

 the former species. 



The bladders are filled with water, and sometimes, 

 include bubbles of air. They bear internally rather 

 short, thick, quadrifid processes arranged in approxi- 

 mately concentric rows. The two pairs of arms of 

 which they are formed differ only a little in length, 

 and stand in a peculiar position (fig. 28) ; the two 

 longer ones forming one line, and the two shorter ones 

 another parallel line. Each arm includes a small 

 spherical mass of brownish matter, which, when 

 crushed, breaks into angular pieces. I have no doubt 

 that these spheres are nuclei, for closely similar ones 



