MANUAL OF NATURAL HISTORY. 335 



several whorls of secondary simple rays, which 

 are destitute of lateral appendages. 

 Of this family, so abundant in former ages, the 



only existing representatives are one or two little 



known tropical species. 



3. FAMILY. Sessile Lily-stars (Holopodidse). Body 

 short, thick; rays dichotomous, convex ex- 

 ternally, grooved along the inside, with nu- 

 merous compressed conical armlets ; oral and 

 anal opening in common (?) * ; sessile or nearly 

 so, and permanently fixed. 

 The only known recent example of this family 



is the curious genus Holopus of D'Orbigny 



SEA-NETTLES. 



In the warmer regions of the globe, the surface of 

 the ocean teems with transparent, fragile beings of 

 delicate organization, sometimes of considerable di- 

 mensions, and possessed of a peculiar stinging power, 

 but oftener of minute size, and only rendered ob- 

 vious by their phosphorescent properties These are 

 the Sea-Nettles (Acalephce), or as they are frequently 

 termed, "Sea-Blubbers" and " Jelly-fishes/' 



They are distributed into groups according to 

 their organs of progression through the water. In 

 the Pulmonigrade forms the animals resemble mush- 

 rooms, sometimes with roots depending from their 



* D'Orbigny. 



