18/8.] AND DASYPUS SEXCINCTUS. 677 



2. Dasypus SEXCINCTUS. 



If now we compare the male organs of Chlamydophorus with those 

 of Dasypus sexcinctus, we shall find that the resemblance between 

 them is very striking. A full description of the male organs of D. 

 sexcinctus after that already given of those of Chlamydophorus trun- 

 catus would be superfluous, seeing that the one would to a large extent 

 be a mere repetition of the other ; and I shall therefore confine my- 

 self to the indication of some points of interest in the anatomy of 

 Dasypus which appear to have been overlooked 1 . The penis is 

 enormous, and in a specimen measuring 13 inches in length, exclu- 

 sive of the tail, is 4 inches long. It closely resembles that of Chla- 

 mydophorus in form, its extremity being simple and not bifid as in 

 the allied genus Tatusia. The integumental covering of the penis is 

 annulated in character, the annulation extending from the base to the 

 extremity of the organ on its dorsal or abdominal aspect, but inter- 

 rupted on its lower surface toward the tip of the organ by a cutaneous 

 patch presenting an altogether different appearance. This patch, 

 which is situated immediately behind the extremity of the penis, is 

 oval in form, and measures 1^ inch in length. It surface is charac- 

 terized by the presence of numerous closely placed transverse ridges 

 of a hard and corneous nature. These ridges give to the patch 

 somewhat of the appearance of a fine file, and, in the absence of a 

 distinct glans, in all probability fulfil the function of the recurved 

 spines so frequently seen on the latter in many mammals. The pre- 

 puce is very small, and, when the penis is fully extended, disappears 

 entirely, being stretchecb-str as to form the cutaneous covering of the 

 latter. In the flaccid condition, however, and when the organ is re- 

 tracted, the penis is withdrawn entirely within the prepuce and almost 

 concealed from view. Improbable as it may appear that an organ of 

 the length of the penis can be really retracted within so small a pre- 

 puce, I am in a position to know that such is the case, having exa- 

 mined two specimens, in one of which the penis was exserted, as in 

 fig. 4, whilst in the other it occupied the position shown in fig. 5. 

 The retraction is accomplished by two retractor muscles, which, 

 arising from the lower surface and outer border of the sacrum, pass 

 forward along the whole length of the dorsum penis even to the tip, 

 fibres being inserted into every part of that surface. These muscles, 

 which exactly repeat those of Chlamydophorus, when contracting, 

 have the effect of throwing the penis into a series of spiral curves, its 

 extremity being bent inwards, as shown in fig. 5, so as to complete 

 the concealment of the organ under its sheath. That these muscles 

 are really the agents in producing this retraction is proved by the 

 fact that the concavity of the terminal curve of the penis is formed 

 by the dorsal aspect of the organ, on which these muscles are placed, 

 whilst the convexity of the curve is formed by its ventral surface 

 which is readily distinguished by the presence of the file-like patch 

 already referred to. The penis is formed, as in Chlamydophoms, 



1 I have been unable to consult Prof. Alexandrini's monograph of Dasypvs, 

 in Mem. Aecad. d. Sci. Bologna, torn. vii. 1856. 



