350 Dr Granfs Observations on the Virgularia Mirahilis. 



Art. XXIV. — Further observations on the Generation of the 

 Virgularia mirabilis. By R. E. Grant, M. D., F. R. S. E., 

 F. L. S., Professor of Zoology and Comparative Anatomy 

 in the University of London. Communicated by the Au- 

 thor. 



In a former notice regarding the structure of the Virgularia 

 mirabilis^ Lam. (Edinburgh Journal of Science, vol. vii. 

 p. 332,) I observed that the small round white ova are seen, 

 in spring, ranged in a double transverse row under each of 

 the lateral fleshy expansions, and that when mature they pro- 

 bably pass out through the bodies of the polypi, as in some 

 other nearly allied zoophytes. This conclusion, founded on 

 analogy, I had an opportunity of confirming by observing the 

 process of generation in this animal in April last. Specimens 

 were brought me alive to Edinburgh from the same part of 

 the Frith of Forth with those of the preceding year, and by 

 carefully supplying them with pure sea water they were pre- 

 served in a healthy condition for several weeks in long glass 

 tubes, that I might more closely examine them with a lens 

 without in the least disturbing their motions. The white ova 

 under the pinnae, close to the stem, were of considerable size, 

 and caused the fleshy substance to project at these parts like 

 small external vesicles. I had the satisfaction, however, to ob- 

 serve the ova advance slowly upwards into the bodies of the 

 polypi which compose the whole substance of the pinnae, and 

 during this passage they acquired a yellowish white colour, a 

 more regular spherical form, and a greater size. As they ap- 

 proached the base of the stomach they appeared to enjoy more 

 freedom, and on examining them in this situation with a lens, 

 through the sides of the glass tubes, I could distinctly per- 

 ceive the ova in the same restless state as I had observed the 

 red ova in the polypi of the Lobularia digitata. They ob- 

 viously contracted themselves in different directions, they 

 changed their positions, and sometimes they appeared as if 

 revolving round their own axis. On escaping from the body 

 they exhibited the same slow spontaneous motions as in the 

 Lobularia. It is interesting to observe this singular law re- 



