570 MR ANDREW MURRAY ON THE PEDICULI 
ever; and Dr Jackson could speak to this fact from personal observation. I ex- 
pressed my disbelief in the supposed disease, and recommended a more searching 
inquiry into collateral circumstances, and, above all, the securing specimens for 
examination. Dr Jackson soon procured these; and neither of us will, I think, 
readily forget the examination of the specimens. Not being supplied with ento- 
mological apparatus, he had put them into an old pomatum pot, which happened 
to be at hand. With justifiable pride he announced that he had secured the 
desiderated specimens, and had three in this pomatum pot, which he had care- 
fully enveloped in several folds of brown paper. On removing the paper, how- 
ever, and opening the pot, to our dismay, instead of the three specimens we 
only found one. The other two had escaped from the insufficiently secured 
vessel ; but whether in Dr Jackson’s pocket or in my room we could not tell. 
Friendship has its limits; and I confess I was unfriendly enough to hope that 
the escape had taken place before the pomatum pot reached me. Fortunately 
their comrade remained hehind to settle the question, that the supposed 
Pediculus tabescentium was only the common Pediculus vestimenti. Dr Jackson 
had further ascertained the fact that although the patient was frequently and 
carefully washed, he was always immediately thereafter re-indued in his old 
dirty flannel jacket, whence the swarms were successively supplied which asto- 
nished beholders; and the further history of the case was, that so soon as the 
dirty flannels were burned, the mysterious disease disappeared, and the patient 
recovered. Such, ] have no doubt, would be found to be the rationale of Lady 
Penruddock’s case, and of all similar recorded cases of the disease of P. tabe- 
scentium, which have obtained credence from not having been examined at the 
time; and believing it to be so, I dismiss that species of Pediculus as a fiction. 
The two remaining kinds, Pediculus capitis and P. vestimenti (the former 
appropriated to the head and the latter to the body), are more embarrassing—for 
hitherto no very good characters of them have ever been indicated. 
I think, indeed, that I have found such characters, but have not examined a 
sufficient series of specimens to be able to decide with certainty. The form of the 
head species is smaller, more elongate, and narrower than the other, and it hasa 
series of dark markings on the margin of the abdomen ; but the body species has 
the margin also similarly margined, only with yellowish instead of dark markings, 
and individuals in both species vary in breadth and length so as greatly to destroy 
the value of the characters drawn from their relative proportions. As might be 
anticipated, their specific distinctness while maintained by some authors is 
denied by others, who consider the larger variety as merely indicating more 
liberal diet and less active habits. As already said, I think they are distinct; 
and in addition to the difference in the general appearance, it will be found that 
the P. vestimenti always wants the spine at the top of the thumb, and has little 
or no projections on the inner side of the penultimate joint—characters which 

