53 
digitorum of that author. I found the tendons separable from those 
of the extensor communis as above stated, hence I take it to be a true 
deep extensor muscle. 
The condition of the corresponding muscle in Chlamydophorus is 
thus described by Macalister* :—“ Extensor indicis (‘ quamvis etiam 
ad pollicis fasciolam fibrosam ablegaret, quae sola pollicis extensioni 
sufficere debet’) arises high up from the ulna as high as the olecranon ; 
it is very large, larger than its neighbour the extensor ossis metacarpi 
pollicis. I found its main tendon passing as usual to the dorsum of 
the index, but a broad slip of fascia stretches along the dorsum of the 
thumb to the last phalanx, justifying the words of Prof. Hyrtl before 
quoted.”’ 
In Tatusia the same author found it also exceedingly large and 
strong, and here it ended in two tendons inserted into the index and 
medius. So also in Orycteropus.t ; 
In Dasypust the tendons are inserted into the index and pollex. In 
Bradypus (didact and tridact)§ the insertion is into the index alone, 
and in Manis (Philodotus, Macalister) Dalmanni)$ into the terminal 
phalanges of each of the first three digits. 
In Manis multiscutatus Macalister|| found no long extensor indicis, 
but the extensor brevis digitorum on the back of the carpus was 
indicial in its insertion. He found the muscle ulnar in origin and 
pollicio-indicial in insertion in Myrmecophag«a. 
In Edentata separate and distinct extensors of the thumbs are rarely 
present, if we exclude the extensor ossis metacarpi as an abductor 
longus. Macalister notes the extensor pollicis longus (secondi inter- 
medii) as a very small muscle in Wyrmecophaga and Manis.‘ . 
Among the Rodentia the extensor indicis is present in many forms, 
amongst others in Hystrix, Arctomys, Custor,** Cavia, Lepus,and Dasy- 
procta.t+ Of these it sends a tendon also the pollex in Lepusty+ and 
Castor (usually)**, so that the muscle represents the extensor secundi 
internodii pollicis as well. In Dasyprocta and others the extensors of 
the thumb are absent. 
In Capromysti a special extensor secundi internodii pollicis is present 
along with the extensor indicis. 
In Chrysochloris among the Insectivora Dobson found extensor indicis 
as a single muscle, so also frequently in Hrinaceus.$$ 
For further details of the morphology of this muscle cf. Gruber’s 
monograph. || || 
Muscles of tlexor aspect of forearm are four in number. 
M. pronator radii teres (figs. 6, 7, 10, 11, 12, and 16, p.r.t.) is 
a muscle of considerable size, and forms the preaxial member of 
the group of muscles arising from the entocondyle. From its 
origin onwards it lies partly under cover of the flexor carpi 
radialis, but a strip of it is superficial. Its origin is partly 
* xxvii., page 258. {xv., page 581. {xiv., page 542. $xxii., page 49. 
and Pl. 252, fig. 1. || xxxv., page 506; Cf. also, xvi., page 252. 4] xxxv., 
page 506. **xxxviii., page 551. {t+ xL, page 405. tf Dobson quoted by 
Leche, xxvi., page 819. §§ lxi., page 45. ||j| 1xi. 
