370 ON THE ATJDITOKT OSSICLES OF EHTTINA STELLERI. 



Manatee, and is situated lower down or closer to tlie foot-plate. 

 This j)late is proportionately broader tlian in Manatus ; so (as the 

 appended measurements prove) it is as wide as the widest expanse 

 of the crura. 



The following measurements (in centimeters) sliow that Mliy- 

 tina possesses a stapes absolutely larger than that of any other 

 animal. It must be remembered that the ossicula of the Sirenia 

 are bulkier than those of the Cetacea. 



Vertical 

 measurement. 



Rhytina V9 



Manatus 1'6 



Halicoie I'O 



Balsena mysticetus .... I'l 

 Balfenoptera Sibbaldii . . 1 '0 I 

 Elephas indicus. 0'6 



In conclusion, it may be said that the malleus of Wiytina is 

 larger than in Manatus ; and therefore it is the largest and 

 bulkiest malleus to be found in the whole section of the animal 

 kingdom where such a bone exists ; that in the characters of its body 

 it resembles Manatus rather than Halicore ; and that in the manu- 

 brium it differs from the other Sirenia, and is far more generalized. 

 The incus is of the Manatus type*, and so is the stapes, which is 

 also the largest and bulkiest stapes to be found in any animal. 



In the appended drawings I have placed the mallei of MJiytina 

 and Manatus in the position best adapted for showing the differ- 

 ences in the manubrium. 



evin' 



A. Malleus of Rhytina Stelleri. .B. Malleus of Manatus americanus. Both 

 natural size and outer aspects. 0. Stapes of Ehytina, natural size. The lettering 

 applies as follows :— «.s. articular surface ; f.b. processus breris ; j).g. processus 

 gracilis ; e.m.n. external surface of manubrium. 



* The body of this bone is bulkier in Macrorhinus than in Ehytina ; but the 

 crura are slender as in other allied Seals. Hence Rhytina exceeds every living 

 animal in the size of all its ossicula. 



