86 PROFESSOR OWEN ON THE AYE-AYE. 
ileum enters, and it diminishes in diameter to the blind end, and, in most, rather suddenly 
about halfway thereto, which has led to the comparison of the cecal half to the 
‘ appendix ceci,’ especially of the human foetus’. In the characters of the caecum, the 
Aye-aye strongly manifests its Lemurine affinities : this gut is scarcely one-fifth the length 
of the body from the muzzle to the tuber ischii, whilst in the Grey Squirrel the caecum 
is half the length of the body. In this Rodent the large intestines are twice the length 
of the body, but they are only one-fourth longer than the body in the Aye-aye. 
The small intestines are rather more than three times the length of the body in the 
Aye-aye, while in the young Squirrel they are seven times the length of the body. 
The divisions of the liver are at, or nearly at, right angles to the surface of the gland 
in the Aye-aye, as in the Lemurs; in the Squirrel they are oblique and deeper, the left 
lobe covering almost all the others. 
The tongue becomes a good test of affinity, owing to its well-marked characteristics 
in the Rodents and Lemurines respectively. The Squirrels, like other Rodents, have 
a short tongue, thick vertically, and especially between the molar teeth, where the 
dorsum rises above the tip, forming the ‘intermolar lobe,’ which commonly bears the 
impress of the palatal furrows. 
In the Aye-aye there is no structure like this: the tongue is thickest transversely, 
has alonger portion free, and, above all, it is characterized by the sublingual firm plate, 
corresponding in general form and structure with that in other Lemuride’. 
The small median supra-thyroid laryngeal sacculus is an indication of the quadru- 
manous nature of Chiromys. fi 
In the vascular system, the disposition of the great veins entering the heart affords 
a test of the affinities in question. In the Sciwride, as in most other Rodents, the 
left trunk of the jugular and subclavian veins passes down the back part of the auricle 
to enter close to the orifice of the post-caval vein: in the Aye-aye, as in the Lemuride 
and all Quadrumana, that venous trunk crosses the fore part of the arteries rising from 
the aortic arch to join the corresponding trunk on the right side and to form a true 
‘ pre-caval’ vein. 
The organs of generation are important indications of natural affinity in the Mam- 
malian class, more especially the male organs, of which the sex of the Aye-aye dissected 
* «« The czecum is long, and terminates almost in a point, and looks like the appendix czci in the human, 
especially the appendix in the foetus.’’—Hunter, ‘ Posthumous Essays and Observations on Natural History, 
Anatomy,’ &c., 8vo, 1860, vol. ii. p. 33 (Stenops gracilis). Schroeder Van der Kolk and Vrolik have made 
the same comparison. ‘‘ Mais il est bon d’observer que chez l’enfant en bas Age et chez les anthropomorphes 
Vappendice vermiforme ressemble assez au prolongement en pointe du cecum chez le Stenops” (‘ Recherches 
d’ Anatomie Comparée, sur le genre Stenops,’ p. 50). 
? Hunter, in Lemur mongoz, L. :—‘‘ The tongue has a part underneath in shape like a bird’s tongue, so that 
it might be called double-tongued” (op. cit. vol. ii. p. 29). See Hunterian Preps. Physiol. Series, Mus. Coll. 
Chir., Nos. 1516, 1517, and 1518; Physiol. Catal. 4to, vol. iii. (1836) pp. 83 and 84; Burmeister, in Tarsius, 
op. cit. 1846, p. 104. pl. 6. fig. 2; Van der Kolk and Vrolik, in Stenops, op. cit. p. 52. pl. 1. fig. 5 5. 
