002 DIDEMNIIJTffl. 



Genus SIGILLINA, Savigny. 



Test gelatinous, solid, elongated, erect, pedunculate, soli- 

 tary or gregarious ; systems single, of many individuals 

 disposed one above another in irregular circles; branchial 

 and anal orifices each with six rays; abdomen larger than 

 thorax; post-abdomen long and slender. 



Ex. S. australis, Savigny, pi. 135, fig. 2. Individual 

 S. australis, fig. 2, a. 



A single species only of this curious form is at present 

 known, from the shores of tropical seas. The name is de- 

 rived from Sigillum, from a supposed resemblance of the 

 common mass to a seal. 



Sub-fam. DIDEMNIIN.E. 



Body distinctly divided into two parts, thorax and ab- 

 domen. 



Genus DIDEMNIUM, Savigny. 



Test coriaceous, polymorphous, sessile, and incrusting ; 

 systems numerous, compressed, without central cavities or 

 distinct circumscription. Individuals scattered ; abdomen 

 pedunculate. Ovary placed by the side of the intestinal 

 loop, increasing in length when the eggs are fully deve- 

 loped. 



Ex. D. candidurn, Savigny, pi. 135, fig. 3. Individual, 

 D. candidurn, fig. 3, a. 



The Tunicaries composing the systems of individuals in 

 this genus are without any appreciable order of arrangement, 

 and are scattered over the common body. The species are 

 found in the European seas. 



