94 CLASS I.— ORDER II. 



The branches are placed on the flat part of the 

 stem ; their divisions, always alternate, have in their 

 length one or two articulations. 



The ovaria, nearly sessile, frequently axillary, some- 

 times dispersed, resemble an antique vase ; at certain 

 times their opening is closed by a lid with a concentric 

 zone. 



Their substance is horny ; their colour a dull and 

 deep fawn ; their height a decimetre. 



Australasia. 



rOUR-CELLED. 



1. Salacia tetracyttara. The only species known. 

 —Plate 6. fig. 3. a. B. C. 



CYMODOCEA. 



Plant-like ; cells cylindrical, varying in length, 

 filiform, alternate or opposite ; stem fistular, marked 

 w4th rings below, plain above, and without interior 

 division. 



These Polypidoms bear a strong resemblance to the 

 Tubularias ; but the Polypi belonging to the last-men- 

 tioned order are always placed at the summits of their 

 branches, whilst those of the Cymodoceas are as con- 

 stantly found on the branches or their divisions. The 

 stem of the Cymodoceas is a continued horny or car- 

 tilaginous tube, simple or branching, and which in a 

 living state should be filled with an irritable animal 



