38 MESSRS. MURIE AND MIVART ON THE 
part being inserted into the pisiform, and part into the fifth metacarpal. This arrange- 
ment is what Mr. John Wood has found in the human subject’. 
Figured in Galago crassicaudatus (Pl. II. fig. 3, and Pl. IV. fig. 13, E.c.w). In 
G. allenii it is large; origin as in L. catta. 
In Tarsius this muscle is represented in tab. 3. fig. 1. 28. 
Extensor inpicis.—This is a very slender muscle, and much shorter than the extensor 
secundi internodii pollicis. It arises from the radial surface of the ulna and the 
interosseous ligaments. Its tendon receives fleshy fibres down almost to the wrist, and 
then bifurcates, going to the index and third digits—that going to the third digit 
sending off a delicate slip to that tendon of the extensor minimi digiti which goes to 
the fourth digit. 
The right and the left sides differed in the specimen of Z. varius dissected by us. 
The left had only a single tendon, going to the index, while on the right side it divided 
into two tendons, going to the third digit and index respectively. 
Cuvier figures this muscle in the above species, but very indistinctly. It seems, 
however, to go to the second and third digits, pl. 69. fig. 1, «”. 
In Z. xanthomystax the belly giving origin to the tendon of the third digit is so 
distinct that it may be regarded as a separate muscle. It is the largest and longest of 
the two, occupying fully the middle third of the ulna. This all but separate slip is 
evidently the homologue of the radial extensor of the third digit, noticed by Mr. John 
Wood in his dissections of the human body with reference to its muscular variations’. 
In G. crassicaudatus (Pl. II. fig. 8, Hz, and Pl. IV. fig. 13, Eui’*) and G. allenii 
there is no extra slip of tendon to the fourth digit; but both of these species possess, 
without doubt, a double extensor indicis, or, in addition to the indicial, an extensor 
medii digiti (Wood). The muscular fibres of the indicial division pass up the higher of 
the two, lying beneath the extensor secundi internodii pollicis. 
According to Meckel* this muscle in Loris is double. The superior and smallest 
portion attaches itself to the index and radial side of the median digit. The inferior is 
inserted in the ulnar side of the middle (third) digit. But Meckel further observes 
that in the Zemwrs, properly so called, the extensor indicis is single, and, indeed, much 
as we have found it in Z. catta. In our dissection of Loris gracilis the extensor indicis 
ended in a single tendon to the index finger. 
Nycticebus* differed in the insertion on the right and left limbs in the specimen 
examined by us. On the right, tendons were given to the index and fourth digits; on 
the left, to the fifth and index. 
The same condition exists in Perodicticus*; but in Zarsius® it springs also from the 
‘ Proc. Roy. Soc. 1866, vol. xv. p. 237, and p. 232. fig. 5, a. 
* Loc. cit. p. 238, and p. 233. fig. 6. 3 Loc. cit. p. 324. 4 P. Z.8. 1865, p. 247. 
5 Loc. cit. p. 37, tab. ii. fig. 12, 0.0. ® Loe. cit. p. 63, tab. 5. fig. 6, no. 38. 
a 
