84 NEW YORK STATE MUSEUM 



may be in this group again straight horizontal, crescent or recurving, exactly 

 as in the other groups and sometimes even the lappet of the sicula, lying 

 opposite the virgella and seen as a blunt mucro in 36, may develop into a 

 long spine, and thus a four spined variety be formed as that represented in 

 figure 35. 



In describing the appendages I have used the terms wings and disks 

 thereby assuming that they are flat bodies of the character of alate exten- 

 sions. Since they are known only in the compressed stage, it is just as 

 possible that they were cuplike bodies or hemispheres, or at least bags in 

 the var. signum. The following facts appear to argue against the latter 

 possibility. The wings are frequently unequally developed, on both sides 

 of the rhabdosome, as in text figure 12, hence independent of each other 

 and not combining into a cuplike body or hemisphere. Their suspension 

 from two spines does not suggest such bodies, nor does the presence of the 

 semicircular disks alongside the wings in var. s i g n u m indicate any great 

 expansion of the appendages. Still there have been noticed in several 

 specimens lappets protruding from behind the wings as in text figure 1 2 

 and in others, as text figure 17, the wings are traversed by horizontal folds. 

 In text figure 16 the test extends to the tip of the virgella and exhibits a 

 marginal thickening. 



Freeh [1897, 553] has cited C 1 i m a c o gr a p t u s bi corn is as a 

 clear case of the development of a rudder aiding in a kind of vertical swim- 

 ming or floating movement and has argued that physae or pneumatophores 

 could impossibly be placed in the center and also at the periphery of a syn- 

 rhabdosome. We do not see any facts combating this view and many in 

 support of it. Some of the latter are that in the formation of the wings 

 there is an obvious endeavor to secure a large surface and their form there- 

 fore reminds more of the tail fins of fish than of anything else ; the) - are clearly 

 but auxiliary organs, for they do not develop in early age, nor in all varie- 

 ties, the variety tridentatus and the Utica mutation lacking them. It 

 is further suggestive in this connection that the size of the appendage is 

 approximately proportional to the size of the rhabdosome, that hence the 



