PER1PLANETA ORIENTALIS. 
233 
Laboratory at Oxford, and in conclusion I have to express my 
thanks to Dr. S. J. Hickson, Mr. G. C. Bourne, and my tutor, 
Mr. E. B. Poulton, for much kind help and advice. 
EXPLANATION OF PLATE XXII, 
Illustrating Mr. Edward A. Minchin’s paper "Note on a New 
Organ, and on the Structure of the Hypodermis, in Peri- 
planeta orientalis.” 
Letters of Reference. 
I — X. The ten terga of the abdomen. P. The glandular pouches, a. The 
anterior extremity of the sixth tergum. r. The transverse ridge across the 
sixth tergum, marking the part of it overlapped by the fifth tergum. d. The 
dark chitinous layer of the cuticle, t. The transparent ditto, h. The hypo- 
dermis. b. m. The basement membrane of the hypodermis. p. The posterior 
extremity of the fifth tergum. c. 1. Chitinous lining of the gland, u. 1. 
Upper layer of small cells of ditto. 1. 1. The lower layer of columnar cells of 
ditto, m. 1 and m. 2. Tergal muscles, g. c. Large ganglion-cells of the 
lower layer of the hypodermis. i. m. Intertergal membrane. 
Fig. 1. — A diagram of the dorsal surface of the abdomen of the £ Cock- 
roach, the fifth tergum being removed to show the two glandular pouches 
placed under the intertergal membrane between the fifth and sixth terga, 
which is represented dotted. 
Fig. 2. — A longitudinal section through the adjacent parts of the fifth and 
sixth terga of an adult Cockroach, somewhat diagrammatic. 
Fig. 3. — Some of the chitinous hairs lining the glands, highly magnified. 
Fig. 4. — Longitudinal section through a gland of a larva of about 8 mm. in 
length. 
Fig. 5. — Ganglion-cells of lower layer of hypodermis, mounted in situ. 
Fig. 6. — Single ganglion-cell of lower layer of hypodermis. 
Fig. 7. — Ideal section of hypodermis and cuticle. 
