248 On Generic Nomenclahire. 



ther into a large oblong or rounder mass, very commonly 

 thrown on the coast, and known by the name of oyster spat, 

 sea roses, wash walls, and several other similar designations. 

 These cases, which do not change their form or size after 

 they have once been deposited, have been considered as 

 corals by Esper and others, though these authors figure 

 the shell which is contained on the side of them. When 

 first deposited, they are rather soft, and contain a cream-like 

 glairy fluid; but they shortly harden, and are, at length, 

 filled with very numerous small, yellow, roundish eggs (a hun- 

 dred or more), from one seventh to one ninth of a line in 

 diameter, which are enclosed in a transparent membranaceous 

 skin, and, under the microscope, appear to be composed of a 

 number of unequal- sized transparent particles, from the 300th 

 to the 100th part of a line in diameter. 



In progress of time, a few of these eggs enlarge, and 

 appear to prevent the developement of the others ; so that 

 only four or five, on an average, come to perfection in each 

 case. When first hatched, the animals are covered with a 

 rather irregular shell, about one line in diameter, some being 

 rather smaller, with acute tips, and others larger and blunt- 

 topped ; so that these eggs must have increased, during the 

 time they were enclosed in the egg-cases (supposing that 

 they only enlarged sufficiently to contain the shells alone), 

 from seven to nine times the diameter they were when first 

 deposited. 



Applying these observations to the egg of Ocythoe, or the 

 animal usually found in the argonaut shells, which I proved, 

 on examination, to be about half a line in diameter (the egg 

 of O. Cranchii being rather larger than those of the Mediter- 

 ranean species), supposing them to enlarge in the same pro- 

 portion as those of Buccinum undatum, the nucleus should 

 be about four or five lines across, which is about the ave- 

 rage size; so that, if there were not other reasons, which 

 I consider unanswerable, such as the form of the body, the 

 non-adaptation or adhesion of the body to the shell, &c, the 

 size of the nucleus would not offer any difficulty with respect 

 to the Ocythoe being the maker of the shell which it in- 

 habits. 



Art. VII. On Generic Nomenclature. By W. E. Shuck ard, 

 Esq., V.P.E.S., Librarian to the Royal Society. 



In a paper on generic nomenclature, published by Mr. 

 Westwood in the last Number of this Magazine (p. 167.), 

 being the continuation of a paper on the same subject in Vol. 



