4 Transactions of the Society. 



specific points of difference he was less felicitous, and some of the 

 points on which he lays particular stress, are, in our opinion, due 

 to his having confused young specimens of Saccamminco sphmrica 

 with adult "specimens of PsammosplicTra fusca. This confusion 

 .nd its consequent errors in descriptive diagnosis have, in our 

 opinion, been largely responsible for the subsequent confounding 

 of the two species, and also for Dr. Ehumbler's attempts to merge 

 the later described PsammospJuvra fusca, v/ith the earlier dis- 

 covered Saccammina sphserica. 



Brady's description of the two species may be quoted witli ad- 

 vantage in juxtaposition with the original description of Psammo- 

 sphsera fusca by Dr. Schulze : — 



Beady. Schulze. 



Saccammina sphserica. Test 

 free or rarely attached. Glo- 

 bular or pyriform, consisting of 

 a single chamber, with compact 

 coarsely arenaceous walls, and a 

 simple orifice situated in a nipple- 

 like protuberance. 



Diam. ^^V to | inch (1 to 3 ' 5 

 mm.). 



Psammosphsera fusca. Test Test free, or attached ; globu- 



free or attached ; spherical or lar, 2 to 4 mm. in diameter. No 



nearly so. Exterior rough and visible aperture. Sometimes with 



coarsely arenaceous. Interior larger grains protruding. In- 



smooth. With minute interstitial terior smooth, 



orifices, Ixit no regular aperture. 

 Colour, reddish -brown. 



Diam. y|o to I- inch (0'16 to 

 4*0 mm.). 



Brady's description of Saccammina spliderica is admirable, and 

 would be sufficient for the complete identification of the adult 

 without figures of any kind, but his description of Psammosphsera 

 fusca contains several points of a misleading nature. The words 

 " interior smooth " can only be accepted in a very limited sense. 

 Some specimens no doubt may be so described, but the species at 

 large has no marked characteristic of the kind. A more important 

 matter for comment is the statement that whilst the test possesses 

 no general and specialized aperture, it has ''minute interstitial 

 orifices." The term is not definitely explained, and some controv- 

 ersy lias arisen around it. In his subsequent account of the 

 species Brady suggests that whilst Psammosplidera fusca possesses 

 no general aperture, protoplasm exudes or protrudes through the 

 " more or less porous tests." Perhaps the interstitial orifices to 

 which he alludes are the exceedingly fine passages occurring be- 

 tween the particles composing the finely granulated cement which, 



