366 Dr. F. Meinert on the Campodee, 
mediale in common, as in Forficula (vide my ‘Anatomia Forfieu- 
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 Japyzx), 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 Podure ; 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 Jess 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 apy additional support that it may still lack +. 
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 im any of 
the true Podure. 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 Nicolet (Rech. p.s. 4 Hist. des Podu- 
relles, p. 47, pl. 4. f. 3, 4) and of Von Olfers (Annot. ad Anatom. Podura- 
rum, p. 11, f.) as entirely erroneous; and so far I agree with Lubbock 
(Trans. Linn. Soe. 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 wasten. 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. | 
