xiii ALCYONARIA PENNATULACEA 363 



are of the usual type. Umbellula appears to be a somewhat rare 

 but cosmopolitan genus in deep water, extending from the Arctic 

 to the Antarctic region in water ranging from 200 to 2500 

 fathoms. 



The interesting genus Chunella was discovered by the German 

 " Valdivia " Expedition at a depth of about 420 fathoms off the 

 coast of E. Africa, and subsequently by the Dutch " Siboga " 

 Expedition at a depth of about 500 fathoms in the Malay 

 Archipelago. According to Ktikenthal, 1 this genus with another 

 closely allied genus Amphianthus should form a new section of 

 Pennatulacea, the Verticilladeae. Chunella has a long and very 

 delicate rachis and peduncle, and the former terminates in a 

 single autozooid and has five or six whorls of three autozooids, 

 situated at considerable distances from one another. Spicules are 

 absent. The full description of this genus has not yet been 

 published, but it is clear that it occupies a very isolated position 

 in the order. 



Sect. 3. Renilleae. This section contains a single family 

 Renillidae and a single genus Renilla (Fig. 160). The rachis 



Fig. 160. Renilla reniformis, a small specimen (34 mm.), showing the dorsal side of the 

 expanded rachis. A, autozooid ; H, the mouth of the axial zooid ; s, siphonozooid ; 

 St, the short stalk. (After Kolliker.) 



is expanded into a flattened cordate form set at an angle to the 

 peduncle, and the zooids are confined to the dorsal surface, which 

 is uppermost in the natural position of the colony. The peduncle 

 is short and does not contain an axial skeleton. The colour of 



1 Zool. Anz. xxv. 1902, p. 302. 



