4f62 WESTWOOD ON THE 



" Voyage de I'Astrolabe,") and from the examination of a 

 specimen now in my collection, it appears clear that the pre- 

 sumed metathorax is the hinder division of the prothorax pro- 

 duced in an extraordinary degree, and covering not only the 

 elytra and wings, but also the real mesothorax and metathorax. 

 I know no instance in which the metathorax is produced so as 

 to conceal the appendages of the mesothorax, or even those of 

 the metathorax. The same enlargement of the prothorax 

 occurs in various singular modes amongst some of the 

 Homoptera. 



In the cursorial Orthoptera some singular variations occur 

 in the distribution of the thoracic segments. In Phasma the 

 prothorax is short, the mesothorax much longer, and in the 

 Apterous species composed of a single piece, without any traces 

 of scutum or scutellum ; and in the winged ones, bearing at 

 its exti-emity a pair of tegmina, between which a slight 

 impression, indicating the scutellum, can alone be perceived. 

 In Mantis, on the contrary, the prothorax is much longer than 

 the mesothorax, the latter and the metathorax being of equal 

 size, each exhibiting an elongated scutellum. But what is 

 the most noticeable is, that whilst we consider the upper surface 

 of the first thoracic segment of Mantis as entirely occupied by 

 the prothorax, its under surface is so similar to the joint under 

 surface of the prothorax and mesothorax of Phasma, as to 

 induce a belief that the portion of the under surface of the 

 prothorax in Mantis, behind the fore legs, cannot be any thing 

 else than mesothoracic. This view is apparently confirmed by 

 the circumstance that the sternum of the prothorax is invariably 

 situated in advance, or at least between, the fore legs, and that 

 there is a distinct piece answering to this description in Mantis. 

 It happens, however, that there is also a mesothoracic sternum 

 quite distinct from this posterior pectoral portion of the pro- 

 thorax. The only way, therefore, in which this structure can 

 be accounted for, is by supposing that the edges of the tergura of 

 the prothorax are deflexed and united behind the prothoracic 

 legs, so as to form, in fact, a cylinder. Now this structure exists 

 in the anomalous genus Raphidia, only the margins are not 

 soldered together ; but in the still more anomalous genus, (and 

 one still more nearly related to Mantis, viz.) Mantispa, the 

 same occurs ; but the margins are united, the union being dis- 

 tinctly traceable. 



