PROFESSOR OWEN ON THE AYE-AYE., 87 
by me permits this application. In all Rodents the peritoneal opening of the serous sac 
of the testis is so wide, and the cremaster so large and so disposed, that the gland can be 
withdrawn into the abdomen, and it emerges into a temporary sessile scrotum only under 
the seasonal enlargement for procreation, which is considerable. Thus, the Rodentia 
are ‘temporary testiconda.’ The Aye-aye has not this organization: the testes are 
permanently ‘scrotal’ after their passage out of the abdomen. 
The Squirrels, like other Rodentia, have distinct ‘vesicule seminales’ with thick 
glandular coats: in the Leporide the vesicula is single, but large. The absence of 
distinct vesicular bag or bags in the Aye-aye removes it from the Rodentia, whilst the 
size and shape of the prostate’ and of Cowper’s glands approximate it to the Lemuride. 
More decisive testimony is given by the penis. The Squirrels and all Rodentia are 
‘retromingents,’ the penis being bent back suddenly upon itself, with the ‘ glans’ 
lying in a prepuce which opens close to the anus. In the Aye-aye, as in the Lemuride 
and other Quadrumana, the preputial sheath of the penis projects freely forward to the 
extent signified by the Linnean character ‘pendulous,’ applied to the ‘ Primates’ 
generally in the ‘Systema Nature.’ 
§ 14. Conclusion. 
The pressure of daily duties and engagements has prevented my further unravelling 
the structure of this little denizen of the woods of Madagascar. I should otherwise 
gladly have pursued the investigation to a degree of completeness more nearly 
approaching that of which Burmeister has left so admirable an example in his ‘ Beitrage 
zur nahern Kenntniss der Gattung Tarsius,’ 4to, 1846. Believing, however, that the 
main points required for determining the moot relationship of Chiromys to the Mam- 
malian orders had been looked to, I felt it due to zoologists to submit the results to their 
judgment, without further delay. 
The first and, to my mind, most congenial reflection that arose on the survey of these 
structures was their adaptive relations to the known way of life and favourite kind of 
food of the Aye-aye. 
This quadruped is stated to sleep during the heat and glare of the tropical day, and 
to move about chiefly by night. 
The wide openings of the eyelids, the large cornea and expansile iris, the 
subglobular lens and tapetum, are arrangements for admitting to the retina, and 
absorbing, the utmost amount of the light which may pervade the forest at sunset, 
dawn, or moonlight. Thus the Aye-aye is able to euide itself among the branches in 
quest of its hidden food. ‘To detect this, however, another sense had need to be 
developed to great perfection. The large ears are directed to catch and concentrate, and 
the large acoustic nerve and its ministering ‘ flocculus ’ seem designed to appreciate, 
«The prostatic glands are two at the basis [or the gland is left there], like 
1 Hunter, in Stenops gracilis :— 
Chir. No. 2564 ; Physiol. Catal. vol. iv. p. 101.) 
the heart on playing-cards.” (See Prep. Phys. Ser. Mus. Coll. 
