1910.] 



Elements of the Mdnnnalian SL-iill. 



427 



surroundino; parts? Until such i)r()l)]cms are to some extent understood it 

 will be difficult to judge for example of the phylogenetic significance of the 

 im})erforate columnar stapes of the Sloths and of Manis (p. 338). Is this 

 truly a persistent primitive character? Is it an indication (possibly like the 

 embryonic characters of the male organ in Sloths) of arrested development ? 

 Or is it a merely secondary loss (as in the Piimipedia) of the stapedial 

 perforation ? What is the significance of the sudden departures from type 

 observable in the ossicula of certain genera ? 



Ethmoturbinal complex. Paulli's researches (quoted liy Weber, 1904) 

 show that the characters of the olfactory bones confirm as far as might be 

 expected the hypotheses of relationship developed in the preceding chapters. 

 xA-S indicated in the subjoined table, the Insectivora seem to be a central 

 Placental type and to have transmitted their olfactory characters with little 

 change to the Chiroptera, Lemuroidea, Rodentia, Carnivora and Hyra- 

 coidea. In the macrosmatic Echidna, Ungulata and Edentata, in which the 

 rhinencephalon is very large the number of ethmoturbinals has considerably 

 increased. In Ornithorhynchus, the Anthropoidea and Cetacea, which are 

 microsmatic, the munber is greatly reduced. The theory of the derivation 

 of the Pinnipedia from the Arctoid Carnivora is strengthened. 



The number and characters of the turbinals in the various orders may be 

 summarized as follows: 



5 <n 



^■^^• 

 o o.S 



C <li ^ 

 0) > 3 



4-1 'm Q 



O 3 m 



s 



3 

 Is 



Remarks. 



Monotremata. 



Echidna. 



Ornithorhynchus 

 Marsupialia. 

 Insectivora. 



Chiroptera. 



Parallels Oryderopus in backwanl extension 

 of endoturbinal series below cribriform plate, 

 from which the scrolls project vertically. 

 Fenestrse cribrosa; represented by a single 

 opening. Aquatic adaptation? 

 Mesethmoid well ossified, ends abruptly in 

 middle of nasal cavity. 



Endoturbinals very generalized. Mesethmoid 

 ends abruptly much as in Marsupialia (at least 

 in Solenodon, Centetes, Erinaceus). In Centetes 

 it grows upward between the frontals. (Bed- 

 dard, 1901). 



