1890.] HELODERMA SUSPECTUM. 191 



tions slender accessory slips, all of which are much the same as we 

 found to be the case in the hand, and which has been quite fully 

 discussed above. We shall dwell more in detail upon these points 

 when we come to describe further on the smaller and special muscles 

 found in the sole of the foot. 



111. Flexor accessorins. — Mivart describes a muscle, which is 

 divisible into two parts, under this name in Iguana (P. Z. S. 

 18G7, p. 797), but it is only its first part that in any way agrees 

 with a muscle which I propose to call by this name in Helo- 

 derma. I find that it arises as a thin, small, fleshy muscle 

 from the posterior aspect of the fibular ossicle of the co-ossified 

 bones of the proximal row of the tarsus and to a limited extent 

 from the adjacent surface of the distal end of the fibula. Soon 

 forming a flat tendon it at once passes to the tarsal aspect of the 

 tendon of the flexor longus digitoruin, where, at a point about 

 opposite the proximal row of tarsal bones, it fuses with it, and thus, 

 as will be seen, constitutes a true accessory muscle to this deep 

 flexor. 



112. Fexor brevis digitorum imperforatus) . — This arises, semi- 

 tendinous, from the dense transverse fascia of the ventral aspect of 

 the ankle, and also from the corresponding surface of the fibular 

 side of the fused ossicles of the proximal row of the tarsal elements. 

 Radiating, it divides into five muscular bundles, which pass in pro|)er 

 order to the five toes ; the one belonging to the hallux being the 

 smallest, while the one jioing to the little toe is the largest. 



The short fasciculus that goes to the hallux is chiefly inserted into 

 the proximal end of the first phalanx of that digit, and simply forms 

 a tendinous tubular sheath through which passes the tendon of the 

 deep flexor, and not a distinct insertional, perforated tendon as is 

 the rule with this muscle in the case of the other toes. We note 

 here that the tendon of the deep flexor sends ott' an accessory slip to 

 every joint as it passes to the distal phalanx for insertion. In the 

 case of the little toe the arrangement is quite similar to what we 

 have just described for the hallux, while the tendon of the deep flexor 

 does not send off any accessory slips to the joints of this digit. 

 With respect to the three middle toes, the arrangement of the inser- 

 tional tendons of the deep and superficial flexors corresponds with 

 the structure of the same ])arts as we described them for the manus. 



113. Lumbricales. — So far as I can discover it is only the tendons 

 of the deep and superficial flexors going to the three middle toes 

 that are supplied with lumbrical muscles, and these are arranged 

 very much as we found them in the hand of the reptile we have 

 under consideration, having quite similar origins and insertions. 



lu this connection we must observe another muscular slip : it 

 arises from the distal surface of the fused ossicles of the proximal 

 row of the tarsus, beneath the origin of the short flexor, and, passing 

 forwards and inwards, it becomes inserted on to the plantar side of 

 the broad tendon of the long flexor in the sole of the foot, before 

 the former splits up to be distributed to the toes. 



1 14. Flexor fibulo-tarsalis. — I find no muscle elsewhere described 



14* 



