r888.] NEW-YORK MICROSCOPICAL SOCIETY. 165 



serves alike for circulation and digestion (gastro-vascular space). 

 The tissues are consistent — not pierced by a system of pores. 

 The osculum is replaced by a mouth, with thread-cells in the 

 epithelial tissues. 



" The PolypomedusLC have an oesophageal tube, with 

 simple gastro-vascular cavity. The generative elements are de- 

 veloped in medusoid forms, which maybe either free-swimming, 

 or permanently attached to hydroid forms. 



"The Trachymedusie are Medusse with a firm, gelatinous um- 

 brella, supported by cartilagenous ridges, with stiff tentacles, 

 filled with solid rows of cells. These may be confined to the 

 young stage. Development takes place by metamorphosis, 

 without hydroid, asexual individuals. The family Trachynemida\ 

 to which Rhopalotiema belongs, is characterized by stiff marginal 

 tentacles, which are scarcely capable of motion. The genital 

 organs are developed on vesicle-like swellings of the eight radial 

 canals." 



Dr. N. L. Britton explained with drawings on the black-board 

 the main points of his exhibit — Seed-coats of the Orchid, Hab- 

 enaria Hookeri, Torr. 



Dr. Britton also donated to the Library of the Society the 

 following publications : Ten numbers of the Bulletin de la So- 

 cie'te Beige de Microscopie; Memoir of the Rev. Elisha Mitchell, 

 D. D.; a.wdi Journal of Ihe £ltsha Mitchell Scientific Society, for 

 1883-84, and 1884-85. 



Mr. Ludwig Riederer explained the mechanism and method 

 of operating the August Becker Sledge-Microtome, exhibited 

 by him. 



Mr. Charles S. Shultz introduced the Rev. E. C. Bolles, D.D., 

 of New York city, who tendered his congratulations to the 

 Society. 



The Vice-President announced from the chair that Dr. H. 

 Hensoldt, an expert lithologist, was expected to illustrate his 

 methods of preparing rock-sections before the Society at the 

 next meeting. 



Mr. William Wales announced the death of Mr. Joseph Zent- 

 mayer, of Philadelphia, and followed the announcement with 

 remarks eulogistic of the character and work of the deceased. 



On motion, the chair appointed the following committee to 



