THE CEPHALOPODA 153 



divided into two by a small median saddle ; a wide 

 external saddle on each side, and a rounded lateral lobe 

 (Fig. 47, b). It is the special feature of the family 

 Gephyroceratida that the external lobe and saddle are so 

 wide that the latter comes to lie in the middle of the 

 lateral area ; hence many authors call it the " lateral 

 saddle." In ontogeny the little median saddle appears 

 late, so that there can be no doubt that the divided lobe 



FIG. 43. ^MANTICOCERAS RHYNCHOSTOMA J. M. CLARKE, UPPER 

 DEVONIAN ; BIG SISTER CREEK, ERIE COUNTY, NEW YORK, 

 U.S.A. (x.) 



Adult, with rostrum and lappets. Last suture-line only shown. 

 (After Clarke.) 



of which it forms part is the external lobe and not a pair 

 of lobes. 



Although the Eifel specimens are never much larger 

 than the specimen described, in beds of the same age in 

 New York there have been found specimens of a closely- 

 allied species which grew to a great size : in these the 

 hyponomic sinus disappeared in age and was replaced 

 by a forward projection or rostrum (Fig. 43). 



