M. E. Hesse on the Pranizse and Ancei. 407 



gone their last metamorphosis and arrived at the state of Ancei; for 

 then the thorax, divided into two distinct portions by a strongly 

 marked constriction, simulates a sort of corselet at the fore part ; 

 greatly developed mandibles, resembling nippers,rival those of the 

 Scarita and Manticorce ; lastly (and this is an extremely curious 

 fact), these appendages, which are so exuberant in the males of the 

 above insects, as in the males of our Crustacea, are wanting in 

 the females of the latter — a character which, however, is not so 

 absolute in the females of the Beetles above mentioned, as they 

 have mandibles like those of the males, but comparatively of 

 very small size ; and, finally, some parts of the thorax present 

 appearances of elytra, as in Meloe "*. 



Metamorphoses undergone hy the Pranizae at their escape from 



the Egg. 



Scarcely have the female Ancei arrived at their final state than 

 their numerous eggs make their appearance in a large mem- 

 branous pouch beneath the thorax. The eggs are of large com- 

 parative size, and of a spherical form ; they are covered by a 

 transparent and slightly rugose skin, through which a single 

 vitellus may be seen ; their incubation occupies from twenty 

 to twenty-five days, but sometimes less, according to the season 

 and the temperature. 



In the first phase of development of the embryo, the mass of 

 matter contained in the e^^ has a flattened oval form, showing 

 at its superior extremity a dilatation divided into three lobes. 

 The median lobe forms the frontal region, and the two lateral 

 ones are the first traces of the eyes or antennae, or perhaps of 

 both. The various parts gradually advance towards perfection, 

 the young Ancei remaining all the time firmly adherent to their 

 mother, and protected by thoracic plates, which cover them until 

 they are capable of seeking their own nourishment. 



At this period the young Ancei have the head and limbs 

 relatively very large; the head is triangular, convex above, and 

 flattened beneath ; the rostrum, which forms the apex of the 

 triangle, is curved downwards. This rostrum presents, including 

 a triangular frontal process which covers and consolidates the 

 whole apparatus, four double symmetrical organs, namely — 



1 . Two large, flat mandibles, forming a pincer, denticulated 

 at the extremities. 



2. Two styliform appendages, likewise denticulated at the 

 end. 



3. Two opercular footjaws. 



* This observation was already made by Mr. Westwood in 1832, Ann. 

 Sd. Nat. t. xxvii. p. 331. 



