446 Boundy — Color Mailings of Carboniferous Gastropods. 



Art. XXX VII. — Original Color Markings of two species 

 of Carboniferous Gastropods ;* by P. V. Eoundy. With 

 Plate III. 



Notices of Paleozoic shells retaining original coloration have 

 been published from time to time but no bibliographic list of 

 such notices appears to have been collected. The appended 

 list, though probably not complete, comprises all the references 

 which I have been able to find. 



Coloration can be recognized as original or inherent much 

 more readily when it takes the form of a design or pattern, 

 than when it appears as a uniform tint overspreading the shell. 

 Of the former type are most of the instances found in the lit- 

 erature as well as the two noticed here. On the other hand, 

 Waagen thought that in a solid dark violet or reddish brown 

 tint which distinguished certain specimens of Productus 

 abichi found in the Salt Range of India, he had found an 

 original color-character of these shells. Another brachiopod, 

 Cleiothyridina incrassata of our American Carboniferous 

 faunas, frequently has the shell of a dark purplish or blackish 

 color, in marked contrast to that of other associated species. 

 Again, specimens of a Spirifer from a certain locality in south- 

 western Missouri are conspicuously tinged with lilac, but this 

 may be due to mineralization. So too, many specimens of 

 Naticopsis of the Altonensis group, which are not uncommon 

 in our Pennsylvanian faunas, are conspicuous by being of a 

 light brown color. This tint, which is more or less superficial, 

 may be due to original coloration, but it may also be the 

 vestige of an epidermal coating. 



In so far as it has been remarked and recorded, coloration has 

 been most frequently retained in the Brachiopods and Gastro- 

 pods, while it is extremely rare in the Pelecypods and Cephalo- 

 pods, though a few of the Orthocerata have been reported 

 with such markings. 



Although original color markings are undoubtedly retained 

 in some of these Paleozoic shells it is much less certain that we 

 have in them the original color. There can scarcely be a doubt 

 that the processes that have obliterated the color in most of the 

 specimens have sadly dulled it on those on which it is now 

 found. 



With the exception of Dielasma hastatum, of which David- 

 son says that he had many examples, instances of coloration in 

 Paleozoic shells appear to be rare and occasional. It is remark- 

 able then to find two species in a single collection which have 



* Published by permission of the Director, United States Geological 

 Survey. 



