Previous studies of the morphology of the humerus in kangaroos showed that the shape of the proximal humerus could distinguish between arboreal and terrestrial taxa among living mammals, and that the extinct “giant” kangaroos (members of the extinct subfamily Sthenurinae and the extinct macropodine genus Protemnodon) had divergent humeral anatomies from extant kangaroos. Here, we use 2D geometric morphometrics to capture the shape of the distal humerus in a range of extant and extinct marsupials and obtain similar results: sthenurines have humeral morphologies more similar to arboreal mammals, while large Protemnodon species (P. brehus and P. anak) have humeral morphologies more similar to terrestrial quadrupedal mammals. Our results provide further evidence for prior hypotheses: that sthenurines did not employ a locomotor mode that involved loading the forelimbs (likely employing bipedal striding as an alternative to quadrupedal or pentapedal locomotion at slow gaits), and that large Protemnodon species were more reliant on quadrupedal locomotion than their extant relatives. This greater diversity of locomotor modes among large Pleistocene kangaroos echoes studies that show a greater diversity in other aspects of ecology, such as diet and habitat occupancy.

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REDUCTION OF SURGICAL HAEMORRHAGEif hypotension is prolonged. (In practice this has very rarely been necessary.)Failure to achieve sufficient hypotension, or to maintain it, after autonomic ganglion block may lead to trouble. If bleeding appears to be severe, replacement therapy is the only measure likely to remove the danger to the patient. Fortunately, failure in suitably chosen cases is infrequent, and the results of failure are rarely serious. I personally have been worried by severe bleeding once only. SummaryThe production of hypotension during surgical operation by blocking the autonomic ganglion with a suitable methonium drug can produce operating conditions of great attraction to the surgeon, can considerably reduce bleeding and therefore add to the patient's safety and post-operative health, and seems to be a safe procedure in skilled hands and with constant observation. It must be realized' that posture plays a large part in producing the desired level of hypotension, and therefore the technique is unsuitable* for certain operations. Some individuals also appear unsuitable, and the individual reaction to the drugs used so far is variable.It must be mentioned that success, or otherwise, in reducing haemorrhage in each individual case has been assessed entirely by the surgeon. Well over three-quarters of the 250 cases have been categorized as "good." ADDENDUM Since this paper was completed the subject has been debated at a meeting of the Anaesthetic Section of the Royal Society of Medicine, with papers from Drs. Enderby and Armstrong Davison. Although the work already done in this field is consequently more widely known, I feel that attention to the basic principles of the technique and the importance of careful selection of suitable cases cannot be overemphasized.Recently a case has been brought to my notice where a patient died two days after an operation for removal of a malignant tumour involving skull and meninges. Hexamethonium bromide had been used to control severe haemorrhage. The patient's blood pressure apparently never rose above 80 mm. systolic during the two post-operative days, nor was any adequate attempt made to raise it. Anuria was absolute for the first 24 hours, but the kidneys excreted some urine during the second 24 hours. Two errors of technique seemed to me to have been made in this case. First, the drug was used late to control already established haemorrhage, instead of at the beginning to prevent bleeding. It is possible that the circulating blood volume had already been dangerously reduced by the time it was used. Secondly, hypotension was allowed to persist for too long without attempts. to correct it by po&ture and methylamphetamine hydrochloride. I think it is absolutely essential, in using this technlque, to maintain a full circulating blood volume and full oxygenation, and to use an adequate dose of the drug to produce successful block and consequent vasodilatation. If extreme hypotension is prolonged beyond a few hours, measures must be taken to correct it.

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