MISCELLANEOUS. 253 



A number of longitudinal ribs, generally eight in any species I have 

 seen, traverse the animal, which in some are crossed by ciliated belts, form- 

 ing the natatory organs ; — perhaps also discharging other functions. These 

 organs are wonderfully tenacious of life : portions continue in motion after 

 the rest of the animal has decayed. 



The mouth, at one extremity of the specimen, is for the most part ex- 

 tremely dilatable. 



The two species of this genus best known in Scotland, are the Berne 

 ovatus, and the Beroe pileus or Pleurobranchia. 



The Beroe ovatus is an ovoidal, transparent, or watery-blue animal, 

 about two inches in length, and half as much in its largest diameter. 

 There is a cleft at one extremity, generally closed, which can dilate as a 

 circular orifice. Eight ribs, broadest in the middle, and diminishing to- 

 wards each end, are crossed by bars furnished with numerous cilia, which 

 cilia seem susceptible of some extension and contraction, if there be no 

 illusion here, for such might possibly be occasioned from the expansion of 

 other parts. 



The dimensions of the ovoidal Beroe are very irregular. Of twenty 

 taken in August, the largest was about two inches long ; but this exceeds 

 the usual size. 



The body sometimes appears streaked with red. and the ribs also 

 reddish. The red seems incorporated with some integral part ; it remains 

 at the bottom of the vessel after decomposition of the animal. Sometimes 

 the whole body has a reddish tinge ; or it is iridescent, one rib appearing 

 purplish, while another is green. The reddish tinge begins to predomi- 

 nate towards the afternoon. These creatures are continually ascending 

 and descending, pursuing a horizontal or irregular course, and tumbling 

 over in the water. 



Having observed some minute transparent globules in the end of 

 March, which were swimming in a vessel that had contained specimens of 

 the Berne ovatus, I subjected them to the microscope. As they proved 

 to be of the same species, I concluded they were the young, not the fourth 

 of a line in diameter. Under the microscope they appearged dingy-white, 

 with red specks, and rather opaque. 



