214 MOLLUSCA. 



in which the individuals are cylindrical with approaching 

 orifices, and the limb of the central cavity not apparent after 

 death, and probably short, as the B. rosaceus, Leachii and 

 Borlassii. In other species, the individuals are ovoid, with 

 remote orifices, and the limb of the central cavity is always 

 apparent and notched, as B. Schlosseri, stellatus, gemmeus, 

 and minutus. In the botrylii conglomerate in which the 

 individuals are disposed in several rows, there is only one 

 species, B. conglomerate. 



GENUS EUCXELIUM. Systems destitute of a central cavi- 

 ty. The individuals are distributed in a single row, and the 

 ovarium is single, sessile, and attached to the side of the ab- 

 dominal cavity. The E. hospiliolum of Sav. tab. iv. f. 4., is 

 the only known species, 



2. Tribe. 



Body free, and moving about in the water. 



GENUS PYHOSOMA. The body is gelatinous, in the form 

 of a lengthened bag open at the widest end. The individu- 

 als are arranged perpendicularly to the axis of the central 

 cavity, super-imposed on one another. The branchial ori- 

 fice is external, without rays, and with an appendage over 

 its upper margin. The anal orifice is opposite, and termi- 

 nates in the central cavity. Branchial sac destitute of folds, 

 with a membranaceous ring at the entry. The branchiae 

 are disjoined. The abdomen is inferior to the branchiae, 

 and not separated by any contraction. Liver distinct, glo- 

 bular, and retained in a fold of the intestine. Ovarium 

 double, opposite, and situate at the upper extremity of the 

 branchial cavity. 



M. Savigny divides the species into Pyrosomata verticil- 

 la', having the individuals arranged in regular prominent rings, 



