82 VOLUTA. 



elaborately painted than the type, the inter-zonal markings form- 

 ing an elaborate network of chestnut-brown veins. 



Moreton Bay, Australia. 



I am unable to separate from this variet} T the shell described 

 by Dr. J. E. Gray as M. Georginse. Mr. Reeve speaks in a 

 knowing manner of " a separate system of characters in M. 

 ducale and M. Georginse" distinguishing the*m from diadema, 

 but he neglects to point out these distinctions. 



Yar. MILTONIS, Gray. Fig. 28. 



Shell more cylindrical, consequently showing more of the 



spire. 



Swan River, Australia. 



Genus VOLUTA, Linn. 



The animal is essentially like those of Cymbium and Melo, 

 but the mantle is not usually so greatly expanded, nor is the 

 foot proportionally so large. 



This genus is oviparous, at least the South American species 

 are so, and M. Duhant-Cilly has given us some interesting par- 

 ticulars concerning them.* He noticed the Yolutes in clear 

 shallow water in Magellan's Straits, and, with the aid of natives, 

 procured specimens which nearly all grasped dead shells of 

 Venus exalbida, a common bivalve of that locality. Upon ex- 

 amining these shells they were found to contain within the cavity 

 of one of the valves, a round, slightly convex membrane, com- 

 parable for size and transparency with a watch-glass. The 

 contents appeared to be merely a milky fluid in some cases, but 

 in others, the egg having advanced further in development, three 

 or four small, but perfectly formed Yolutes could be seen swim- 

 ming in the fluid, which had become transparent. D'Orbigny 

 also "I" collected large numbers of these eggs, and in the month of 

 February saw the j^oung Yolutes, four of five in number, in each. 

 The containing membrane, which becomes corneous, he describes 

 as 80 to 100 millimetres in length, more than half the size of the 

 animal which lays it, and he conjectures that it expands after 

 coming into contact with the water. 



* Revue Zoologique, 167, 1840. f Voy. Am. Merid., 424. 



