94 SAGAKTIADJi. 



sometimes three or four inches "below the surface. They 

 are all equally sensitive, shrinking on the slightest alarm." 

 Mr. Holclsworth . found the species under circumstances 

 "which deceived him into the belief that it was a per- 

 manently free form, and he accordingly named it Scolanthus 

 sphcero'ides.* "The specimens were found near low-water 

 mark, imbedded in the fine chalky mud which fills the 

 crevices of the rocks at Seaford, their expanded disks being 

 just level with the surface, but so nearly covered that only 

 a faint star-like outline was visible ; on being touched they 

 instantly disappeared; and so great was their power of 

 inversion and contraction, that on digging carefully, they 

 were generally found about one-and-a-half inch deep, and 

 having that peculiar bead-like form which has suggested 

 the specific name of sphcero'ides. There was usually a 

 depth of six or seven inches of mud below them ; so that 

 they could not have been fastened to the rock ; and since I 

 have had them at home, now nearly five weeks, they have 

 not shown the least inclination to attach themselves to 

 the gravel, or glass sides of the tank in which they are 

 living; ; three of them have burrowed into some sand on 

 which they were placed, but the others remain on the sur- 

 face and are but rarely contracted. Soft mud is probably 

 their natural habitat, being the most easily penetrated; 

 and I could find no traces of any of these animals in a con- 

 siderable tract of sand only a few yards from the locality 

 whence these were obtained." 



My friend was subsecjuently convinced that he had been 

 misled by the appearance of the specimens : he examined 

 them with me, and kindly gave me one of his original 

 specimens, and we were both convinced that they were of 

 this species. The apparent perforation at the rounded pos- 

 terior extremity could have been nothing more than the 

 * Proc. Zool. Soc. ; May, 1S55. 



