964 Miscellaneous. 
Reasons for supposing these Organs to be Respiratory. 
1. There are no other organs which could be supposed to be 
respiratory in function. 
The tubes are chitinous, and the chitin grows thin and mem- 
branous towards the end, affording a good opportunity for interchange 
of gases. 
3. The tube ends project into the pericardium, so that they are 
bathed with the blood. 
a The tubes are filled with air. 
. The organ is so placed as to aérate the blood just before it 
rt to the heart. 
In Scutigera the dorsal scales do not agree in number with the 
ee The organs are arranged on the dorsal scales; that is they 
are not arranged in correspondence with the mesoblastic or primitive 
segmentation (see a former paper before this Society, ‘‘ The Post- 
Embryonic Development of Julus terrestris,” 1888). This renders 
it probable that they are not a primitive development, but a recent 
modification, agreeing with the fact that all other Myriapods breathe 
by the more primitive method of trac shew. 
This mode of respiration differs from that in other Myriapods in 
the following particulars :— 
1. The tubes are collected into one definite organ, instead of being 
distributed about the body. 
2. The tubes have no spiral thread. 
In acting on the blood just before it returns to the heart, so 
that aérated blood is distributed instead of unaérated. 
It resembles the trachee of other Myriapods in the following 
particulars :— 
In the air-sac into which the tubes open. 
Tn the cylindrical form of the tubes. 
In the branching of the tubes. 
The organs resemble the tracheal lungs of Spiders— 
1. In the large air-sac. 
2. In the number of tubes opening into an air-sac. 
3. In the arrangement for bathing the tubes with blood in a 
blood-sinus. 
4, In the supply of aérated blood by the heart. 
They differ from them in— 
1. The form of the tubes, which in Scutigera are cylindrical. 
2. In the absence of the membrane which in Spiders surrounds 
the organ. 
I therefore hold that the respiratory organ in Scutigera holds a 
position intermediate between the trachew of Myriapods and the 
lungs of Spiders. I hold with A. Leuckart (‘ Zeitsch. fiir wiss. 
Zool. > vol. 1. p. 246, 1849, * Ueber den Bau und Bedeutung der sog. 
Lungen bei den Ar achniden ” ) that the trachee have developed into 
the lungs of Spiders a and Scorpions, and I think that the organs in 
question form a series of which the lowest term is the trachee, the 
next the organ of Scutigera, then the lungs of Spiders, and then of 
Scorpions. Proe. Roy. Soc. No. 303, pp. 200, 201 (Nov. 26, 1891). 
