1884.] 



MICROSCOPICAL JOURNAL. 



43 



which screws on just like an objective, 

 has a jam-nut to keep it secure. 



The advantages of this nose-piece 

 are that it is very small and light, the 

 objectives with the rings attached fit 

 in their boxes, and objectives are 

 readily attached and removed from 

 the stand with one hand, almost in- 

 stantaneouslv. 



New Members of tlie Iiifiisori.al 

 Order Chojino-Fbigellata, S. K. 



BY DR. ALFRED C. STOKES. 



n. 



It has seemed surprising to the 

 writer that the beautiful little zooids 

 which the latest authority has grouped 

 together under the title of choano- 

 flagellata not only remained so long 

 unseen by human eyes, but that even 

 after their discovery by the distin- 

 guished observer in our own country. 

 Prof. H. James-Clark, they were not 

 again recorded from America until 

 their rediscovery in English and Ger- 

 man waters. The cause could scarcely 

 have been in their minuteness, al- 

 though that is sufficiently conspicu- 

 ous, if anything so small can ever be 

 considered conspicuous, to tax the 

 best of good objectives in the study 

 of their structure. Aside, however, 

 from the extreme delicacy of their 

 membranous and collar-like food- 

 trap, and the length of the filament- 

 ous foot-stalk and flagellum, there is 

 little about them to compel a good 

 lens to pass them by unseen. It is 

 true that to study the collar a high- 

 power objective of the best class is 

 needed, but to search for them as 

 they live on the leaflets of submerged 

 plants, and even to make out the 

 contour of their bodies, only a good 

 glass of medium power is demanded. 

 The writer has little trouble in finding 

 them by searching about the Myrio- 

 phyllum and other aquatic weeds 

 bearing similarly dissected leaves, 

 with a Tolles' ^*f-inch objective, 90° 

 to 1 20° aperture. Yet it must be re- 

 membered that in this case familiarity 

 leads to a confidence in the ordinal 



identity of the brilliant object that 

 greater amplification seldom destroys. 



The reader surely understands that 

 I am not making the absurd claim 

 that an unknown infusorian o.cxx)2- 

 inch long can be identified with a 

 -j*jy-inch objective. But for an obser- 

 ver familiar with the appearance of 

 the choano-flagellata such a glass will 

 suffice to pick them out, and to an 

 educated eye it will, among the sal- 

 pingoeca? more especially, frequently 

 indicate their species. I refer to this 

 particular objective by the lamented 

 Mr. Tolles because I have had no ex- 

 perience with any other of the same 

 denomination. The members of tlie 

 order to which these papers more 

 particularly refer, however, although 

 first noticed with the Tolles objective, 

 were studied with Bausch and Lomb's 

 homogeneous ^, N. A. 1.43, and a 

 similar immersion -j^^, N. A. 1.35, by- 

 Spencer, and a water-immersion ^ 

 of 175° by the former makers. 



Whatever may have been the cause, 

 these exquisite flowers of the lakes 

 and seas were apparently forgotten 

 imtil Mr.. W. Saville Kent discovered 

 in England Prof. James-Clark's spe- 

 cies of Codosiga and Salpi7igceca ^ 

 adding many new forms to those gen- 

 era, besides establishing the genera 

 Monosiga^ Astrosiga^ and Desma- 

 rella. In Germany little has been 

 done among them ; in our own coun- 

 try still less. Whether this is because 

 of their minuteness, the small number 

 of observers, or the use of French 

 triplets, is a question ; but the fact 

 remains, and is all the more a cause 

 of wonderment when we consider 

 their abundance and almost cosmo- 

 politan habitat. 



The following presumably unde- 

 scribed species of Codosiga (fig. 12) 

 is a very characteristic form, found in 

 considerable numbers attached to the 

 dead and decaying leaflets of JMyrio- 

 phyllum from an aquarium. Aside 

 from its distinctive shape, it has one 

 marked peculiarity which has not be- 

 fore come to my notice with any other 

 of these creatures. It is that of fre- 



