366 Dr. F. Meinert 07i the Campodepe, 



mediale in common, as in Forficula {vide my 'Anatomia Forficu- 

 larum/ p. 51); but in this family the third pair of spiracles 

 belongs unquestionably to the metathorax alone ; and when the 

 abdomen is furnished with spiracles (in Japyx), the segmentum 

 mediale has, like the other abdominal rings, its own pair, inde- 

 pendently of the one belonging to the metathorax. As yet, no 

 spiracles have been discovered in Podurse ; but, according to my 

 observations, their organs of respiration consist merely of an 

 open canal along the underside of the head and the thorax, and 

 it is in the fore end of this canal under the head that the tra- 

 cheal system opens, whenever it exists, as in some of the larger 

 Smynthuri*. 



The abdomen presents three divisions, of which the segmentum 

 mediale forms the first, the three following rings the second, 

 whilst the remaining six rings form the third division ; in Japyx 

 the separation between the first and second division is less con- 

 spicuous than in Campodea. The number of abdominal rings is 

 unquestionably ten, all furnished with muscles for independent 

 motion, and all complete, having both ventral and dorsal shields. 

 It seems, therefore, that every doubt as to ten really being the 

 typical number of rings in the abdomen of insects must now 

 disappear ; and I believe a careful comparison between the 

 structure of the abdomen in these animals and in Forficula will 

 give to my interpretation of the structure met with in the latter 

 genus any additional support that it may still lackf- 



The first seven ventral shields of the abdomen carry in each 

 of their hind corners a short appendage articulating with the 

 abdomen, such as is also found in Machilis, but not in any of 

 the true Podurse, They possess two cerci, which, as in Ulonata, 

 belong to the last ring of the abdomen, whilst the cerci of Po- 



* I look upon the statements of Nieolet (Rech. p. s. a I'Hist. des Podu- 

 relles, p. A"], pi. 4. f. 3, 4) and of Von Olfers (Annot. ad Anatom. Podura- 

 rura, p. 11, f.) as entirely erroneous; and so far I agree with Lubbock 

 (Trans. Linn. Soc. xxiii. p. 441). 



t [It may be remembered by some that this question has been the 

 subject of a prolonged controversy between the late Dr. Schaum and Dr. 

 Meinert, the former having, in a paper " On the Composition of the 

 Head, &c." in Ann. Nat. Hist. vol. xi. 1863, maintained that the typical 

 number of abdominal segments in insects was nine, whilst Dr. Meinert, in 

 his ' Anatomia Forficularum,' which appeared shortly after, maintained that 

 the proper number was ten. The discussion was continued by Dr. Schaum 

 in two papers in ' Archiv f. Naturgeschichte ' (vols. xxix. & xxx.) and by 

 Dr. Meinert in ' Naturhistorisk Tidsskrift,' vols. ii. & iii. It turned mainly 

 on the correctness of Dr. Meinert's interpretation of the structure of the 

 abdomen in Forficula, and this is strongly borne out by a comparison 

 with Japyx and Campodea ; but the former of them was then not yet de- 

 scribed, and the latter Dr. Schaum does not seem to have known or taken 

 into account. — Translator's note.'\ 



