390 EVENINGS AT THE MICROSCOPE 



this strange display, we will begin to examine the per- 

 formers more in detail. A slender creeping thread, irreg- 

 ularly crossing and anastomosing, so as to form a loose 

 network of about three meshes in width, surrounds the 

 margin of the Sabella 1 s tube, adhering firmly to its exterior 

 surface, in the chitinous substance of which it seems im- 

 bedded. Here and there free buds are given off, especially 

 from the lower edge; while from the upper threads spring 

 the strange forms that have attracted our notice. These 

 are spindle-shaped bodies, about iVth of an inch in height, 

 whose lower extremities are of no greater thickness than 

 the thread from which they spring; with a head -like lobe 

 at the summit, separated from the body by a constriction, 

 immediately below which two lengthened arms . project 

 in a direction toward the axis of the tube. 



Such is the external form of these animals, and their 

 movements are still more extraordinary. The head -lobe 

 of each one moves to and fro freely on the neck, the body 

 sways from side to side, but still more vigorously back- 

 ward and forward, frequently bending into an arch in 

 either direction; while the long arms are widely ex- 

 panded, tossed wildly upward, and then waved down- 

 ward, as if to mimic the actions of the most tumultuous 

 human passion. 



"Whenever the Sabella protrudes from its tube, these 

 guardian forms are pushed out, and remain nearly in con- 

 tact with the Annelid's body, moving but slightly; but 

 no sooner does it retire than they begin instantly to bow 

 forward and gesticulate as before. These movements are 

 continued, so far as I have observed, all the time that the 

 Sabella is retracted, and are not in any degree dependent 

 on currents in the surrounding water, whether those cur- 



