47 



inches in length, and apparently not capable of much change of 

 form. 



<S. unisemitay St. Calcareous plates of body irregularly oval, 

 commonly pierced with four holes, deposited in many layers. 

 Those supporting the stems of the tentacula and the bases of the 

 suckers more elongated, but in other respects similar. 



The suckers differ from those of other species in having no 

 terminal plate ; they are in fact almost destitute of calcareous 

 matter, a few minute pieces only being found on the sides. 



The tentacula are harder and more rigid than those even of 

 Sclerodactyla^ but much less ramose, and have the calcareous 

 deposits arranged in a different manner. 



The pieces of the oral circle present a remarkable peculiarity, 

 in being uniform ; the alternate ones, to which the longitudinal 

 and singularly slender retractor muscles are attached, not being 

 bifid anteriorly. 



The digestive and respiratory organs are less largely devel- 

 oped than in most species. 



Dr. C. T. Jackson read a description and analysis of 

 Botryoidal fibrous Phosphate of Lime, from Crown Point. 



Last February, I received from Mr. C. F. Hammond, of 

 Crown Point, N. Y., several well characterized specimens of 

 the Eupychroite Phosphorite, discovered some years since by 

 Prof. Emmons, and described by him in his Report on the Ge- 

 ology of New York. It was first analyzed by Prof. Lewis C, 

 Beck, who ascertained its chemical nature, and published his 

 analysis in the Mineralogy of New York, page 240. It being 

 desirable for scientific purposes to have a new and more minute 

 analysis of this mineral, I undertook it, in connection witli the 

 researches I was making on the Phosphate of Lime, of New 

 Jersey. The specimens sent me by Mr. Hammond differ 

 somewhat from those described by Prof. Emmons, — his being 

 green, while mine are brown or pale bluish gray. The surface 

 of the botryoidal concretions is covered with a thin film of Iron 

 Pyrites, which is easily scraped off. In preparing the speci- 

 mens for analysis, this crust was carefully removed, and only 

 the pure mineral was employed. It occurs in botryoidal masses 

 of a fibrous structure, and is composed of alternate layers 



