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Show 174 DR. R. W. SHUFELDT ON [Apr. 1, the flexor perforans digitorum, but they are more forcibly brought to our notice at this point in our dissections. In the case of the second digit, which we still have under consideration, it is seen that when the tendon of the flexor perforans digitorum has passed through the perforation of the flexor perforatus digitorum, it in turn sends off a very delicate tendon which is perforated in its turn by the tendon of the/, perforatus digitorum, and which thereafter becomes inserted into the base of the second phalanx immediately posterior to the insertion of the tendon of the same. Again, when the tendon of the/. perforans digitorum passes the second joint of this second finger it sends off still another delicate tendon, which this time becomes inserted into the phalanx just referred to, at a point just posterior to its head. Finally, I find upon closer observation that in the case of the muscular slips which are thrown off on the part of the slip-tendons of the /. perforans digitorum in the palm of the hand, and which go to be inserted into the bases of the proximal phalanges of the third and fourth digits, that they so divide that the muscular slip between the second and third, as well as between the third and fourth metacarpals goes partly to the base of one finger and partly to the other, on either hand, for insertion. W e will now consider the method of insertion of that slip of the / perforatus digitorum which serves the third digit. This is very peculiar. Its main tendon is inserted into the palmar aspect of the distal extremity of the second phalanx, and is duly perforated near its middle by the proper tendon of the deep flexor. In addition to this it throws forwards still another and a delicate tendon, which in turn is inserted into the base of the phalanx just mentioned. This last tendon is perforated at its middle by the tendon both of the first-described tendon of the/. perforatus, as well as by the tendon of the/ perforans digitorum. W e find here, also, that the tendon of the deep flexor sends off a delicate slip opposite each phalanx of the digit under consideration, which, in every case, becomes inserted into the several phalanges immediately posterior to their heads. The arrangement in the case of the fourth digit is essentially the same as that we have just described as obtaining in the third. In the fifth digit it is also the same, but the /. perforatus digitorum does not possess the auxiliary perforated tendon. Comparing this with what Sanders found in the corresponding parts in Liolepis belli, we find them to be quite different in many particulars, as the reader may see by referring to that anatomist's work upon the reptile to which I allude. On the other hand, I am unable to compare these parts with the corresponding ones in Iguana tuberculata as they are offered us by Professor Mivart, for the reason that that investigator omitted to give a full account of the details as to the manner of insertion of the deep and superficial flexors in the form he selected for their demonstration, and in his drawing of the same the integuments have not been removed from the phalanges (P. Z. S. 1867, p. 785, fig. 6). One would hardly look for such a high degree of specialization in the matter of these flexors of the hand of Heloderma as the reptil |