REPORT OF THE STATE PALEONTOLOGIST 1901 613 



bodies (specially Devonic bodies) are so much alike that what- 

 ever course of argument applies to one seems of necessity to 

 apply to the rest, the more as they are concurrent in the rock 

 strata. Yet in these bipartite shields we find a closer analogy, 

 if any, to the ammonoid aptychi of the Mesozoic, so far as the 

 division of the shield is concerned. It has been argued by 

 various writers that the tenuous chitinous substance of these 

 bodies is purely a result of preservation. Calcareous substance 

 is frequently destroyed in bituminous shales; hence the cal- 

 careous layers of these bodies may have been thus removed, 

 leaving only the organic film. Specimens from the sandstones 

 ;ire however equally devoid of trace of calcareous layer. It has 

 furthermore been contended that these presumable aptychi, on 

 the decomposition of the animal's body, have been fioated by 

 the waves unable to transport the heavy shells, and have hence 

 been accumulated by themselves in other sediments than the 

 latter; a plausible contention could w^e but find some more 

 satisfactory^ ground in the structure of the " aptychi " for 

 ascribing this cephalopod function to them. 



In the Paleontology of New York, v. 7, we figured the sole 

 instance known from the rocks of this state of the concurrence 

 of any of these bipartite bodies with a gouiatite. Here is a 

 specimen from the soft Naples shales, presenting a body 

 whorl of M a n t i c o c e r a s p a 1 1 e r s o n i, the diameter of 

 whose shell originally was not less than 3 inches. On and with- 

 in its body chamber lies a Dipterocaris or at least an object 

 having the doubly cleft outline of the species so denominated. 

 This little body has a length of about 5 mm. This concurrence 

 may, of course, be quite as casual as the usual dissociation of 

 these bodies. If, however, this be takin as an indication of 

 relationship between the ammonoid and the Dipterocaris, 

 it is not the relation of aptychus or oi)erculum. However, in 

 view of all the present evidence, we can not divest ourselves 

 of the belief that there is nevertheless some organic connection 

 between these Devonic bodies and the cephalopods; for, while 

 we lack any further confirmation of the latter than that above 



