VOL. Xm.] PHILOSOPHICAL TRANSACTIONS. 56^ 



of one side was as big again as the other. The colour of the testes was white, 

 as is usual, and so was their substance. I took notice of the vasa praeparan- 

 tia, which had nothing uncommon : but the deferentia (i, i,) were remarkable; 

 for though they ran in a straight line almost from the testes to the penis, and 

 formed no large body, yet this duct was so often involved, that were it unravelled 

 and extended its whole length, it would be twice as long: which made me think, 

 that it was only the extension of the epidydymis, for the whole testis is but a 

 congeries of curiously convoluted vessels which terminate in the epidydymis, 

 whose continuation makes the deferens : and where its convolutions are many 

 upon the body of the testis itself, there the deferens is an even duct ; but 

 as in our subject it making no such body there, or but a very small one, in its 

 passage downwards it was every where crimpled, and about the middle of the 

 kidneys often convoluted, which is represented in our figures. 



Where they emptied themselves I could not so well observe in the rattle-snake, 

 since the parts which I had laid out for making the scheme soon dried, before I 

 had an opportunity of nicely examining them. But since upon the dissection 

 of a viper I found that they (fig. 3. a) were continued along the penis single, 

 where the penis was so; and afterwards divided, and ran to the end of each. 

 Nor were there any vesiculae seminales or prostatas here to receive them ; and a 

 reason for it, I shall allege when I have described the penes (fig. 2. K), which 

 here were very remarkable, not only for their structure, but number likewise ; 

 there being 4 in all, two on each side, which lay sheathed in the body, that 

 upon first opening it they were not to be perceived, but only the large orifices 

 where they were drawn in as a finger of a glove may be by a thread fastened to 

 the end. But having protruded them by a probe, they appeared as is represented 

 in (fig. 2.) And I observed that towards the basis, or root, they were single of 

 each side, and that here they were thick beset with prickles, whose points looked 

 backwards, and were very sharp ; and seemed, especially when dry, like the sub^ 

 stance of the bristles of a hedge-hog: but hence they were divided, and 

 formed two round bodies, of the size of a small goose quill, about 4 of an inch 

 long of a red colour ; but the whole, as protruded, was above an inch long. 

 When protruded I found they could easily be retracted, and drawn in by 

 the help of large muscles, (1, 1,) that were fastened to them and ran along 

 under, and were at last inserted at the end of the tail at the setting on of the 

 first rattle; which upon the trial was so plain that we need not doubt of the use 

 of them, and I shall therefore call them retractores penum. But Charas seems 

 to mistake them in vipers, for the penes themselves; which he describes to have 

 their origin from the extremity of the tail ; as does Baldus Angelus Abbatius,* 



* De Viperae natur. et facultat. cap. 19, pag. mihi 60.— Orig. 

 VOL. II. 4 D 



