189 5.] MICROSCOPICAL JOURNAL. 195 



ing equivalents in the various tropical seas, the student 

 would naturally turn to the question of their agreement 

 or correspondence or lack of correspondence in certain 

 anatomical relations or bearings. By suitable compari- 

 son it will at once be seen that there are traces of dis- 

 similarity between fossils of the Mississippi marl and 

 the recent species of Holothurian epidermal structures. 

 The anchors occurring in the marl have barbed prongs, 

 and the shield-like plates are more numerously perforat- 

 ed with holes having serrated edges, while the wheel- 

 plates in their dry state exhibit a webbed space uniting 

 the six spore-like rays which radiate from center to mar- 

 ginal rim, the inner edge of the rim showing a serrated 

 arc, thus forming a plate-like surface. But in such an- 

 chors of recent species as I have been enabled to exam- 

 ine, I found no trace of barbs on their prongs, and the 

 shield-like plates had few perforations, and those were 

 quite large. They had an open slender skeleton of 

 meshes. The wheel-plates do not clearly indicate any 

 other structure than that of six radiating spokes with- 

 out any discernable web uniting them. 



Those who are familiar with the beautiful and elabor- 

 ate rosette preparations of diatoms, anchors, wheels and 

 shields of Synapta and Chirodota, and stellate spicules, 

 as prepared and sent out by noted -European artists in 

 this class of work, for the delectation of American pat- 

 rons, will appreciate the use made of these little 

 adornments of the Holothurians (sea cucumbers), which 

 are gathered from the bays of the Indian Ocean and 

 Mediterranean Sea and elsewhere. These are compara- 

 tively unknown in their unprepared state in the United 

 States, through the educating medium of mutual ex- 

 changes of microscopical material. 



And while on the subject of preparations containing 

 arranged Holothurian plates, etc., I will state that the 



