174 DR. R. W. SHUFELDT ON L^P^- U 



thejlexor 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 turu 

 by the tendon of they, 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 f. p)erforans digitorum passes the second joint of 

 this second finger it sends off still another delicate tendon, w'hich 

 this time becomes inserted into the phalanx just referred to, at a 

 point just posterior to its head. Finally, I find upon closer observa- 

 tion tiiat in the case of the muscular slips which are thrown off on 

 the part of the slip-tendons of the f. 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. 

 We will now consider the method of insertion of that slip of the 

 f. perforatxis 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 oi the f. perforatus, as well as by the tendon 

 of the/, perforans digitorum. We 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/, jt^^'foratus digitorum 

 does not possess the auxiliaiy perforated teudou. 



Comparing this with what Sanders found in the correspond- 

 ing 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, 1 am unable to compare these parts with the corresponding 

 ones in Iguana titberculata 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 reptile 



