On Clialcidites inhabiting the Arctic Region. 407 



tutes a kind of little utricle with rather thick walls, truncated and 

 open at the summit ; while the placenta, elongating and growing 

 proportionally, forms a small ovoid body which exactly fills the 

 cavity of this young ovary, but without exhibiting the slightest 

 adhesion to its walls. In this state it resembles a young solitary 

 ovule. 



" A new modification now soon presents itself and becomes 

 more and more marked. The little ovarian utricle contracts as 

 it increases in length ; thus its orifice in a short time becomes 

 elevated to the summit of a little truncated cone, which is the 

 commencement of the style. At the same time the young pla- 

 centa is a little contracted towards its free extremity, so that its 

 form is now turbinated, and its point generally fills up the infe- 

 rior opening of the styliferous canal. Its surface, which until 

 then had remained smooth, quickly swells into little rounded 

 papillae which are the commencement of the ovules. These ovules 

 in Dodecatheon, Primula and Cortusa are numerous and arranged 

 spirally." 



These facts, of which the commissioners (M. A. Brongniart, 

 M. A. Richard and M. Gaudichaud) guarantee the exactness, 

 sufficiently prove that in the Primulacece the placenta has a ba- 

 silar origin ; that it is developed as an internal verticil without 

 any adhesion either to the walls or summit of the ovary ; that it 

 is there isolated like the nucleus of an ovule, or rather like a ter- 

 minal spine; this evidently proves the spiral arrangement of 

 the ovules, and still better, a little terminal flower perfectly 

 formed, observed by M. Duchartre in Cortusa Matthioli. 



This important memoir contains many delicate observations 

 and curious facts, but as to give these would be to reproduce the 

 memoir itself, the commissioners confine themselves to drawing 

 attention to the capital fact of the free central placenta altogether 

 independent of the walls and summit of the ovary, which is fully 

 demonstrated, and to declaring that all M. Duchartre has de- 

 scribed and figured is incontestably true. 



LI. — On the species of Chalciditcs inhabiting the Arctic Region. 

 By Francis Walker, Esq., E.L.S. 



[Continued from p. 342.] 



Encyrtus Cleone, fem. Viridis, scutello cupreo, antennis pedibusquc 

 fiavis, parapteris albis, alis limpidis. (Corp. long. lin. | ; alar, 

 lin. H.) 



Body convex, bright green, minutely squameous : head large, 

 transverse, slightly impressed in front, a little broader than the 

 thorax : eyes round, red, rather large and prominent : ocelli form- 



