1882.] 



MICROSCOPICAL JOURNAL. 



188 



closely resembling that of Thuricola 

 ( Vaginicold) valvata, consists in a 

 delicate membrane attached to the 

 inner wall of the lorica opposite to 

 the valve, and at a point about mid- 

 way between the origin of the latter 

 and the orifice of the sheath. It is 

 shown in optical section in figure 38. 

 It extends arcuately upward and in- 

 ward, and receives the edge of the 

 valve as it descends upon the con- 

 tracted animal. It is flexible, bend- 

 ing at the touch of the ascending 

 zooid, but is rigidly attached to the 

 lorica, and is stiff enough to make a 

 well-defined indentation in the soft 

 substance of the animalcule. It sup- 

 ports the edge of the closed valve at 

 about the beginning of its middle 

 third. The valve, although the con- 

 nection could not be demonstrated, 



Fig. 38. Thuricola Innixa, n. sp. 



is probably attached to a ligamentous 

 prolongation of the body, since it be- 

 gins to rise before coming in contact 

 with the expanding zooid. 



Thuricola innixa^ n. sp. Lorica 

 sessile, transparent, sub-cylindrical, 

 four to five times as long as broad, 

 truncate, and somewhat tapering pos- 

 teriorly, bearing at some distance 

 from the orifice an internal valve-like 

 appendage as in T. valvata, and an 

 opposite, rigidly attached, but flexi- 

 ble, membranous organ projecting 

 arcuately inwards, and acting as a 

 support to the edge of the descend- 

 ing valve, the wall of the lorica being 

 dilated laterally immediately behind 

 this, in optical section, bristle-like 



valve-rest ; body pedicellate, hyaline, 

 projecting when extended one-third 

 its entire length beyond the orifice of 

 the lorica ; pulsating vesicle anterior, 

 contracting once in fifteen seconds. 

 Hab. Pond water, attached to the 

 leaflets of Ceratophyllum j not com- 

 mon. 



The Microspectroscope.* 



The spectroscope is an instru- 

 ment for analyzing and comparing 

 light from different sources. It con- 

 sists essentially of a narrow slit 

 through which the light to be exam- 

 ined first passes, a lens focussed upon 

 the slit to render the rays parallel, a 

 prism to decompose the light, and a 

 telescope for magnifying the spectrum 

 for examination. The ordinary labora- 

 tory spectroscope of the chemist gives 

 a spectrum only a few inches in length, 

 but in order to map the lines in the 



Fig 



Zeiss' Spectral-ocular. 



solar spectrum far greater dispersion 

 is required, and the light passing 

 through the narrow slit of one of the 

 largest spectroscopes has been spread 

 out into a spectrum over twenty feet 

 in length. 



The principles of spectrum analy- 



* Read before the New York Microscopical 

 Society. 



