320 PALAEONTOLOGY OF NEW YORK. 



priority over von Helmersen's A. variabilis), is from the Permian of northern 

 Russia. Davidson recognized no species in the British formations, though King, 

 in 1850,* considered his Productus umbonillatus (^P. latirostratus, Howse) an 

 Adlosteges. Davidson described A. Dalhousii, and Waagen A. Medlicottianus, 

 from the Permian of the Salt-Range of India. In America but two species 

 have been referred to this genus, namely, A. Guadalupensis, G. C. Shumard, from 

 the Guadalupe Mountains of Texas, a very imperfect shell, insufficiently illus- 

 trated, but showing a high cardinal area ; and A. spondyliformis. White and St. 

 John, from the Upper Carboniferous beds of Iowa ; a form which it would be 

 difficult to separate from Strophalosia on the basis of the features given in 

 the original description and figures. 



Mr. R. Etheridge, Jr., in discussing " Adherent Carboniferous Productidae,"f 

 has figured (figs, 2-4) and described a shell which he regards as Chonetes, 

 adherent by its spines (figs. 2, 3) and the outer surface of the pedicle-valve to 

 foreign objects. This discussion is one of great interest and will be referred to 

 at greater length in regard to some important points established in this and a 

 previous paper on the same subject, by Mr. Etheridge. There is some room for 

 doubt, however, whether these shells should be regarded as belonging to the 

 genus Chonetes. The individual represented in figure 4 of his work, a pedicle- 

 valve with area and delthyrium, attached by its outer face, and covered with 

 spines creeping over the surface of the host, can hardly be anything but a 

 Strophalosia of the type of S. radicans, S. Keokuk and S. scintilla. The subject 

 of the other figures, a shell in which one of the cardinal spines encircles a 

 spine of Productus, is quite imperfect but has a more decided chonetiform ex- 

 pression. It will be interesting to learn more of this peculiar form. 



* Annals and Magazine of Natural History. 



t Qaartrrly Journal Geolog'ical Society, vol. xxxiv, p. -198. 1S7S. 



