66 Proceedings of the Royal Irish Academi/. 



scarcely dilated ; males slightly incurved at the tail ; dimensions as 

 above. 



The other species, P. Aonycis, of vi'hich I have only obtained two 

 specimens, both females, occurred in the peritoneal cavity of the large 

 Indian Otter from the river Indus {Aonyx leptonyx var. Ilayoii) sent home 

 by the late Earl of Maj'o to the Dublin Zoological Gardens (whose 

 anatomy I have described in the Proceedings of this Academy, Vol. I. 

 Series II., Science, p. 539). These parasites measured 17-20»2to. in 

 length, and were straight, elongated, acuminated, with nearly conical 

 apex and an obtusely truncated head which is 25mm. in width. It is 

 closely annulated with 30 rings, each of which is sharply defined and 

 separated from its neighbours by a shai-p- edged, square-p.rofiled furrow. 

 These rings, from being very wide {0-7 mtn.) posteriorly, become very 

 narrow in front and cease to be distinct at the head. The mouth has two 

 lateral chitinous lip-ridges, one on each side. The two pair of hooks are 

 elongated, acute, with longer basal fulcra than in P. imperatoris (four 

 times the length of the exserted portion of the hook), but with a much 

 shorter basal process. There is a single bilobed epipharyngeal nerve 

 ganglion, and the oviduct, ovary, and digestive tract are arranged on 

 the same plan as in P. imperatoris. 



The surface of the skin is covered over with numerous, irregularly 

 arranged circular dots with depressed edges ; these are most numerous 

 about the head and forepart, but become fewer posteriorly. There 

 were no ova in any forward state of development. 



XII. — On the Muscular Anatomy of CnoLCEPus Didactylus. By 

 H. W. Mackintosh, B. A. (With Plate 4.) 



[Read November 9, 1874.] 



In the month of January last. Professor Macalister having purchased* a 

 fine specimen of Cholcepus didactylus from Mr. Gerrard of London, 

 kindly afforded me the opportunity of studying its anatomy. JN'otwith- 

 standing the peculiar habits of this animal, it does not seem to have 

 received much attention from myologists. The fullest description is that 

 of Professor Humphry (Journal of Anatomj^ and Physiology, November, 

 1869), and even that is incomplete in many points, which, however, is 

 easily accounted for from the fact of many of the muscles having become 

 decomposed ; Mr. Galton, in his Paper on Dasypus (Transactions of the 

 Linnean Society, XXVI.), mentions four of the muscles, and Professor 

 Meckel is stated by Professor Humphry to have alluded to the muscular 

 anatomy of this animal, but I have not been able to corroborate this. With 

 a view to supply this defect as far as possible, we made a thorough ex- 

 amination of our specimen, and were surprised to find in it many points 

 of difference from its congener Bradypus, although the identity of 



* Out of the grant of money given to him by the Council of the Eoyal Irish 

 Academy for procuring specimens for examination. 



