ANATOMY OF THE LEMUROIDEA. 93 
anterior lumbar vertebral. 18. A double tendon of origin is possessed by the rectus 
femoris. 19. The tensor vagine femoris is absent, or only rudimentary fibres are 
extant, in Cheiromys, Nycticebus, and Galago crassicaudatus. 20. The biceps femoris 
is simple, or only slightly modified in attachment and muscularity. 21. There is no 
peroneus tertius. 22. Those species examined possess an extra and superficial layer of 
palmar and plantar interosseous slips. 23. All the genera have a short tendon which 
unites the flexor sublimis and the flexor profundus digitorum muscles previously to their 
usual digital divisions. 
There is nothing of a very singular nature in the muscles distinguishing any one 
genus from its fellows. As regards characters of a positive or negative kind that have 
been observed by us or by others, they may indeed be inconstant; nevertheless we place 
- the undermentioned on record. 
I. Lemur.—l. The temporalis assumes a partly double layer, in this respect exhibit- 
ing structure pointing towards Rodents and Carnivora. 2. In L. xanthomystax the 
stylo-hyoid is pierced by the digastric muscle. (Meckel distinguishes a muscle in 
Lemurs as the “ masto-styloidien.”) 
Il. Galago.—No myological structure is peculiar to this genus, unless the absence of 
a pectoralis minor is a normal condition in G. allenii. 
II. Loris and Nycticebus.—These are alike, except that the former in one instance 
examined by us had no psoas parvus. 
IV. Tarsius—1. The psoas magnusis said to be double. 2. The vastus externus has 
also two bellies. 3. There are, according to Burmeister, but two adductors of the thighs. 
V. Perodicticus.—Van Campen has asserted that in the Potto the following muscles 
are wanting:—1. The anconeus. 2. The levator clavicule. 3. The serratus posticus. 
VI. Chetromys.—The curiously constructed Aye-Aye differs muscularly from its 
kindred, in alone having 1, a double semitendinosus, and, 2, in the trapezius over- 
lapping and hiding the insertion of the levator clavicule. 
We shall now place together the several genera which exhibit alliances or similarities 
with reference to the development of muscles or the distribution of tendons. At the 
same time we do not attach equal weight to all these seeming affinities, as some may but 
represent irregularities of tendinous distribution such as happen in Man; others, again, 
are more suggestive and better to be relied on as balancing characters of family 
relationship. 
Group I. Lemur, Galago, Cheiromys, and Tarsius. 
1. In the first three genera that anomalous muscle the rotator fibule is undoubtedly 
found: it may possibly be also extant in Tarsius (?), though the accurate Burmeister has 
not described such a structure. 
2. A plantaris muscle exists in the genera under consideration. 
