141 



pellicle forming the true pupa-skin ; the tipper part of the head beinjif, moreover, siu- 

 mounted by the transverse lunate piece of the induraled head-covering of the larva, 

 through which the two horus of the so-called pui)a had been protruded. This lunate 

 piece is represented by Reaumur (Mem. iv. pi. 3.'?, fig. 6, d, d) ; and as, in looking at 

 the head from the front, the ojieii space belween the upper part of the pellicle and the 

 lunale piece is seen to be traversed by two internal prolongations of the horns, ex- 

 tending to the pellicle itself, it seemed not improbable that these two horns are the 

 antenna-cases. 



Mr. Westwood further directed attention to the statement made by Mr. Curtis, 

 that the death's-head moth, on emerging from the chrysalis, has its legs enveloped in 

 thin pellicles, subsequently cast off; and suggested whether this pellicle was not ana- 

 logous to the thin skin cast by the May flies after their first flight, and which appears 

 equally to be identical with the thin pellicle covering the bodies of the pupae of coarc- 

 tate Diptera, such as that of the Eristalis mentioned above. Monsters of this kind 

 are of great rarity, a Noctua described by Miiller (' Naturforscher,' St. xiv. pi. 4, figs. 

 1—3), and a butterfly, Nymphalis Populi, figured by Wesmiiel (Bull. Acad. Bruxelles, 

 t. iv. No. 8), being the only recorded instances. A Dytiscus, however, in Mr. Bowring's 

 collection, and an Emperor moth in Mr. Stephens's cabinet in the British Museum, 

 also agree with the preceding, retaining, in the perfect state, the head-covering of the 

 larva. 



Mr. Waterhouse exhibited two species of Donacia which he had compared with 

 the Leptura aquatica and L. sericea of the Linnean collection. The latter is the 

 Donacia sericca of modern authors; the L. aquatica ofLiniifeus diff'ers in being a 

 rather shorter and stouter insect. In D. sericea the thorax is broadest in front, and 

 considerably contracted behind the middle : the anterior angles are as prominent as 

 the lateral hump or swelling which lies immediately behind them. In L. aquatica the 

 thorax is rather shorter, nearly quadrate, less contracted behind ; the anterior angles 

 are not so prominent as the lateral hump, and this hump is rather smaller ; the surface 

 of the thorax is more rugulose, and the dorsal impression is more distinct. In 

 D. sericea the 'third joint of the antenncB is elongate-obconic, and decidedly longer 

 than the second ; whilst in L. aquatica the third joint of the antennas is short-obconic, 

 and very little exceeds the second in length. In botli sexes the antennae are longer in 

 D. sericea than in L. aquatica; the legs are also rather longer. In L. aquatica the 

 tooth to the hind femora is stouter, and the joints of the tarsi are shorter and broader. 

 Such are the differences which present themselves upon comparing the insect exhibited 

 to the Society, as being similar to the L. aquatica of the Linnean collection, with the 

 Donacia sericea. Mr. Waterhouse could not say whether these difierences are all of 

 them constant. The specimen exhibited was taken at llannoch, in Perthshire. 



Mr. Waterhouse observed that since the last Meeting he had examined certain 

 Cassidse in the Linnean collection which might be referred to British species. They 

 were : — 



1. Cassida viridis. This is not, as has by many been supposed, the C. equestris, 

 but is ihe species commonly found by us on thistles, having acute posterior angles to 

 the thorax, and punctate striae to the elytra, = C. rubiginosa of Bohemann. 



2. C. nebulosa = C. nebulosa of Bohem. 



3. C. Murraea = C. murraea of Bohem. The rufous-brown variety. 



4. C. maculata = C. murrcea of Bohem. The green variety. 



5. C. nobilis = C. obsoleta of Bohem. Has the margins of the elytra reflexed, 



