162 PROCEEDINGS OF THE ACADEMY OP 



Anodonta Napoensis. — Testa L-evi, oblongo-elliptica. subcompressa, valde 

 insequilaterali, antice et postice rotundata ; valvulis subcrassis ; natibus pro- 

 minulis ; epidermide teuebroso-fusca, encarpifbrmi, flexuosa, obsolete radiata ; 

 margarita jiallido-viridi, non iridesceate. 



JIab. — River Napo, Equador, S. Am , Prof. Orton. 



Bescriptious of UNIONIDJ£ from the Lover Cretaceous Formation of New 



Jersey. 



BY ISAAC LEA. 



Prof. Cope very kindly placed in my hands the specimens of Uidonidxvfhich 

 he collected in a bed of bluish clai/, now first observed to contain them, about 

 six miles north-east of Camden, N. J. This bed is subordinate to the Green 

 Sand, so long known to our geologists as belonging to that portion of the Cre- 

 taceous group which furnished so many interesting organic remains within the 

 last forty years, particularly the Iladrosaurus Foulkii, Leidy, and the Lmlaps 

 aquilunguis, found by Prof. Cope. The same member of the Green Sand For- 

 mation has been very productive also of marine mollusca, some of which I de- 

 scribed in our Proceedings from the beds near Haddonfield, N. J. But, as ob- 

 served above, no fresh water remains had been found in these cretaceous beds 

 there, and the unexpected development of these Unionidie by Prof. Cope, it is 

 hoped, may lead to other and more extensive results. 



These interesting beds in New Jersey have only yet had a very slight de- 

 velopment. They will, no doubt, continue to yield their natural treasures to 

 the industrious investigator for many years. The late Prof. Vanuxem, as early 

 as 1818, while examining the Paris basin, was convinced that these New Jersey 

 beds had their equivalent in the Green Sand of Europe ; and subsequently, in 

 1828, his notes were published in the Journal of the Academy, where he gave 

 a table of their " relative geological position." 



Prof. Cope procured nearly forty specimens of Unionidse, and these are com- 

 posed of teu species, viz. : eight Uniones and two Anadontse. These consist 

 almost altogether of casts, but the forms are well preserved, and in some spe- 

 cimens the inner layers of the nacre are remaining in fragments. These frag- 

 ments, submitted to the microscope, exhibit the imbricated structure as de- 

 veloped by Prof. Carpenter in the Unionidse, but I could not detect any of that 

 portion of the outer structure of the nacre where the base membrane is de- 

 posited in the peculiar cellular structure described and figured in his work. 

 The impress of the muscular cicatrices is visible in many of the specimens. 

 These cicatrices being placed in their usual positions, shewing even the dorsal 

 and palleal scars. While all the massive structure of the cardinal and lateral 

 teeth have been decomposed and carried off, their impress in the clay remains 

 perfect, showing the same forms and striaB which are found in the massive 

 cardinal and lamellar teeth of our western species. 



As there are no characters of the shell itself left in any one of the specimens, 

 to designate specific differences, either by form of teeth, color of nacre, or epi- 

 dermal rays, it remains only to take the outline, transverse diameters, and 

 general curves, to group these specimens. In so doing, I have made these 

 groups conform to the most known species, and named them accordingly. 

 Among these specimens I have noticed none which have nodules or folds, 

 while there is a general resemblance in size and form to those now inhabiting 

 the rivers of the Ohio basin. 



As the bed in which these fresh-water shells are found lies below the well- 

 known deposits of " green sand or marl beds," it becomes a very interesting 

 question as to its relations to these superimposed beds. Further investigation 

 can alone give us the data to settle this point. In finding these fresh-water 

 molluscs here, we are naturally brought to consider how far they may have 

 relation to the products of those deposits in Europe, where the same genera of 



[June, 



