Metamotyhosis of a Species of Cassida, 523 



Ciivier and Valenciennes, in which the lateral scales extend no 

 farther than the ends of the rays of the pectoral fin, the whole 

 length of the posterior portion of each side being smooth and 

 soft, without scale or fold of skin. The principal dorsal spine 

 is smaller in this species than in either of the other two. The 

 dorsal fin has ten rays, pectoral eleven, anal eight, caudal 

 twelve. The general colours of all three species are green 

 above, passing into silvery white below ; but several of the 

 specimens I have preserved in spirits exhibit various shades 

 of crimson and purple, as mentioned by your correspondent. 

 Messrs. Cuvier and Valenciennes speak with less confi- 

 dence of the specific distinction of the half-armed species {b) 

 than of the other two (vol. iv. p. 493, 494-.): but I am 

 happy to be able, in confirmation of their views, to state, 

 that, besides possessing examples of the three sorts from 

 other localities, I succeeded, on different days during the 

 month of August last, while fishing for whitebait in the 

 Thames near Woolwich, in taking many, both young and 

 adult, of all three species ; but the first, as before stated, is 

 by far the most common. 



I am. Sir, yours, &c. 



William Yarrell. 

 Rj/der Street, St, James's, Sept, 4. 1830. 



Art. VIII. On the Metamorphosis of a Species of Cassida. By T. H. 



Sir, 



I NEVER peruse your amusing Magazine without a con- 

 sciousness of my indolence in not having contributed my mite 

 to its entertaining pages. I cannot offer you subjects of much 

 miportance, but I shall be content, if what I may present to 

 your notice should prove acceptable and be deemed worthy of 

 room in your publication. 



The paper I have now to offer is in illustration of the 

 metamorphosis of a species of Cassida ; one, as curious as I 

 have met with in the insect tribe. The drawing [fig. 128.) 

 exhibits a species of Cassida, pretty common in the botanical 

 garden near Calcutta; I found it abundantly spread over the 

 foliage of a fine Convolvulus, almost to the destruction of every 

 leaf. The larva is of an ovate form, depressed ; it is in length 

 about half an inch, and one quarter of an inch broad, very 

 soft and tender, and so delicate in texture, that the intestines 

 and circulation are evident with the aid of a lens. It has 

 six short flattened legs, which are hid in the pinnated sets? 



M M 2 



