188 



GENERA 



33ELONGING TO THE SECOND ORDER OF THE THIRD 



CLASS. 



ANABYOMENA. 



A FAN-FORMED Polypidom, with articulated and 

 symmetrical nerves, almost transparent, and enve- 

 loped in a gelatinous substance. 



As only one species is known to constitute this 

 genus, it has long remained a doubt whether to class 

 it with animal or vegetable productions : even the 

 power of chemical analysis has been found insufficient 

 to solve the difficulty, as many Thalassiophytes ap- 

 pear to yield almost the same productions as this Po- 

 lypidom ; nor does the microscope assist us in dis- 

 covering any part we can consider as fructilicative. 

 Analogy remains our only guide, and has induced me 

 to place the Anadyomena among the animal creation. 

 No marine plants, whether articulated or not, pre- 

 sent the slightest resemblance in their organization 

 to the object in question ; but that is not wholly the 

 case with respect to Polypidoms, many of which are 

 equally deficient in polypean cells. The substance 

 of the Anadyomena, however, seems to be of the same 

 nature as that of many of the Sertularias, and Tubula- 

 rias; it is much more horny than that of the Thalassio- 

 phytes, and possesses a degree of stiffness and trans- 

 parency which is common to some Polypidoms, but 



