ANATOMY OF THE LEMUROIDEA. 3 
it better to figure Galago crassicaudatus. We have not, however, thought it necessary 
to rewrite the whole of the descriptions, and have therefore retained L. catta as our type 
in the text. 
The skeleton, dentition, and brain of the animals composing this group having already 
been extensively investigated and compared the one with the other, we think it super- 
fluous to retread the same ground. In the present memoir, therefore, omitting the 
consideration of those structures, we rather confine ourselves to a comparison of some 
external points, the muscles, the viscera, the generative organs, the blood-vessels, and 
the nerves of the several genera of the suborder. The present communication treats 
only of the external points ahd the myology. 
Except where distinctly stated, it is to be understood that we have not been able to 
ascertain any divergence from the structure of L. catta in the other species or genera of 
Lemuroidea here referred to. 
As regards the genera Perodicticus and Tarsius, however, we are unable to say as to 
some points whether there is an agreement or not, owing to the silence of the authors 
already mentioned respecting certain myological details. 
The loss the Society sustained in the death of their fine specimen of Aye-Aye (Chei- 
romys madagascariensis) has been to us a gain, inasmuch as it has supplied us with the 
means of comparing Professor Owen’s myological description with nature, and of adding 
details which he did not deem it necessary to state, but which are useful for our 
comparisons. 
I, On soME EXTERNAL CHARACTERS. 
The object of the present memoir, as has been stated, is chiefly a comparison of the 
internal anatomy of the group; but, considering the correlation between external form 
and internal structure, we cannot altogether pass over the former in silence. ‘This 
appears to us necessary, as the whole of the Lemuroidea, in spite of their seemingly 
great diversity of type, have strong external family resemblances accompanying those 
common characteristics of internal anatomy which separate them so sharply from the 
higher Primates. 
The external characters differentiating the various groups of the suborder have already 
been sufficiently described by previous writers. We propose, then, simply by a few 
remarks to direct attention to:—Ist, the general form of the body; 2nd, the head and 
ears; 5rd, the conditions presented by the extremities. 
1. General form of the Body and Limbs. 
Great as is the difference which seems at first sight to exist between such an animal 
as the Ring-tailed Lemur (Lemur catta), our type, on the one hand, and the Slow Loris 
(Nycticebus tardigradus) on the other, yet the whole of the Lemuroidea, from Jndris to 
Cheiromys, agree together in the following points. 
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