THE AMERICAN 



MONTHLY 



MICROSCOPICAL JOURNAL. 



Vol. IX. JUNE, 1888. No. 6. 



Analytical Key to the Fresh-water Polyzoa.* 



The Polyzoa are so plentiful in our ponds and slow streams, and so ex- 

 quisitely beautiful, that those who are loyers of nature, although not profes- 

 sional naturalists, should be more familiar with them than the majority of 

 such people seem to be. The amateur microscopist. or the adyanced one 

 indeed, can find no more attractiye field for investigation than that occupied 

 by the fresh-water Polyzoa. They abound almost eyerywhere in our ponds 

 and lakes. They encrust the lower surfaces of the stones, the floating log, the 

 lily stems ; they cling to the rootlets of Lcmtia^ and even form huge, slightly 

 adherent, or often floating, inasses of jelly, into which the charming animals 

 retreat at the least alarm, and from which they spread their lovely plumes 

 when they feel that all is well. They are, therefore, easih' obtained. ' It is 

 the first step that costs,' and here the first cost to the beginner consists in 

 learning to recognize the colonies with the naked eye. 



The jelly-forming PectinatcUa produces gelatinous masses, varying with 

 age from the size of a pea to that of a man's head, or larger ; the color being 

 pale reddish or a flesh tint. The masses are adherent to almost any submerged 

 object in still water, becoming easily detached when old, and then often 

 floating just below the surface. When in this condition, the colonies fre- 

 quently contain many scattered white spots, quite visible to the naked eye. 

 The beautiful animals secreting and living within this gelatinous aggregation 

 can be seen only with a good pocket lens ; to properly examine them a com- 

 pound microscope is needed. This also holds good in reference to those forms 

 which encrust submerged objects with their tubular colonies ; a microscope 

 and some patient care being needed, for the little creatures ai^e timid. Once 



Explanation of Plate. 



Fig. \. — Urnatella gracilis. After Leidy. Slight- Fig. 12. — Lophopus Trembleyi. After Jullien, from 



ly altered. AUman. Life size. 



2. — Plumatella repens. After Jullien. i-i,.- Pectinatella mas:nifica. Outlines of a col- 

 3. — Plumatella hici/uga. After Jullien, from ony, reduced in size. After Jullien, from 



Hancock. Slightly enlarged Hyatt. 



4. — Plumatella arethusa. After Jullien, from 14. — Pectivatella magnifica. Young colony, en- 

 Hyatt. Life size. larged. After Hyatt. 



5. — Plumatella diffusa. After Jullien, from 15. — Cristatella ophidioidea. After Jullien, from 



Hyatt. Life size. Hyatt. Reduced in size. 



6. — Frede7icella sultana (Plumatella luci/uga). i6. — Paludicella Ehrenhergii. After Jullien, 



After Jullien, from AUman. Life size. from Allman. Life size. 



7. — Fredeiicella sultana (Plumatella luci/uga). 17. — Norodonia Cambodgiensis. After Jullien. 



After Jullien, from Allman. Colony, enlarged. 



8. — Fredericella regina. After Jullien, from 18. — Norodonia Cambodgiensis. Cell enlarged. 



Hyatt Life size. 19. — Norodonia Sinettsis. After Jullien. Col- 

 (j.—J-'redericella regina. After Jullien, from ony, enlarged. 



Hvatt. 20. — N. Sinensis. After Jullien. Cells enlarged. 



10. — Hyalinella vesicularis. After Jullien, from 21. — Hislopia lacustris. After Jullien, from 



Hyatt. Carter. Colony, enlarged. 



II. — jlyalinella vitrea. After Jullien, from 



Hyatt. Life size. 



'From the Joui nal 0/ the 'J t enton Natuj al PJistory Society, }anu3Lry, \i&-;. See Frontispiece. 



