D. Keilin and G. H. F. Nuttall 321 
shortening and malformation of the left side of the thorax, causing a lateral 
curvature of the insect’s body as illustrated. 
Leg abnormalities in Arthropods, especially in insects, are not rare; in 
hitherto recorded instances they consist, however, in the duplication and not 
in the fusion of adjoining members as illustrated in our specimen. 
Abnormalities confined to gonopods and ventral plates. 
(Text-fig. 26.) 
In Lot N. 229 e, P. humanus race capitis from a Tamil boy, Federated Malay 
States, were found four females with abnormal gonopods. Specimens I and 
II show a tendency on the part of the gonopods to fuse as illustrated at (A); 
the gonopods approach each other in the median line whilst the intermediate 
space is much reduced in size and the minute hairs are few and abnormally 
disposed (compare with Text-fig. 5). The ventral plate is sub-triangular and 
placed at a considerable distance from the fused gonopods. 
Text-fig. 27. Pediculus humanus race capitis 9, abnormal. Lot N. 2G0, from an East Indian 
boy, British Guiana. The last abdominal segment is deformed. (A) dorsal and (B) ventral 
aspect. (N. del.) 
Specimens III and IV show the complete fusion of the gonopods in the 
median line. They form a single strongly chitinized process bordered with 
sensory hairs, some of the latter encroaching in one instance (C) upon the 
outer surface of the structure. A minute pit, lying centrally, appears to 
represent a vestige of the inter-gonopodial space. 
Abnormality of posterior abdominal lobes of female. 
(Text-fig. 27.) 
In Lot N. 260, P. humanus race capitis from an East Indian boy, British 
Guiana, we found a female with the last abdominal segment asymmetrical, 
the left posterior lobe being hypertrophied so as to overlap the opposite lobe 
ventrally. The chitinization of the last segment and its structure is very 
unequal, as illustrated. 
9 ]_ 9 
