11 PROCEEDINGS OF THE ACADEMY OF 



fossil is at all identical with the European species ; but it is not sufficiently 

 distinct to warrant a separation with the amount of material collected. 



There can be no doubt, however, that this species (even were it found in 

 the same beds with " G. Tucumcarii"), is certainly distinct from that species, 

 The principal points of difference are G. calceola(?) is a short abrupt oyster, 

 with a large surface of attachment, and in every instance yet known with the 

 beak totally obliterated. It is found in a bed not only with very different 

 lithological characters, but belonging to a different horizon from those con- 

 taining the G. Pitcherii. 



The "plicated oyster, closely allied to 0. Marsha," is in several important 

 points very distinct from that species. It has been called by Mr. Meek 

 0. Englemannii. It is of the type of 0. Marshii, has strong plications, but 

 differs mainly in the area. I have examined twenty or thirty specimens, and 

 compared them with all the figures of the European species to which I have 

 had access. The area of 0. Marshii is at least four times as long as that of 

 0. Englemannii. There are other characters also which would serve to distin- 

 guish them ; as yet, the true O. Marshii has never been found in America. 



Through the kindness of my friend, Dr. J anew ay, I have obtained some 

 specimens of Gryphaa Pitcherii, from the Indian Territory, near the Choctaw 

 mission, and I believe I now have the means of proving the identity of the 

 true G. Pitcherii with the form called by Prof. Marcou, G. dilatata, var. 

 Tucumcarii. 



With the aid of Prof. Marcou 's figures, 1 to 3, pi. 4, on one hand, and Dr. 

 Morton's types on the other, I have an unbroken series of gradation from one 

 form to the other. I have exhibited the suite to a number of the best 

 naturalists in Philadelphia, and no one has been able to show a break in the 

 series. Mr. Conrad, after a careful examination, pronounced them to be a 

 regular gradation from one variety to another of the same species. 



Dr. Morton's original specimens, now lying on the table, as well as the last 

 sentence of his descriptions, show that the beak is "distinctly incurved." 

 Prof. Marcou refers a form to this species in which the beak is strongly deflected. 

 This form, unknown to Dr. Morton, is, I have no doubt, distinct. I have 

 recently gone over the whole subject carefully, with the following results : The 

 oblique, carinated form is a distinct species, and must be called Gryphaa navis. 

 The species described by Morton is the same as the one called Tucumcarii by 

 Marcou. The small specimen figured by Morton is said by Marcou to be 

 " incomplete and without the superior valve." This is not so. The specimen 

 is a young one, but is very perfect. Dr. Rcemer did not see it, because it was 

 lost some time before his visit to Philadelphia, and afterwards discovered by 

 me among some rubbish. The beak and umbone are round, there is no 

 carination, and the figure in the Synopsis will convey a very correct idea of 

 its form. It is as distinctly lobed as the figure 1, pi. 4, of Geology of N. A. 



The large specimen, spoken of by Dr. Morton, from the plains of Kiamesha, 

 is more nearly of the form of figure 3 of the same plate. There is every form 

 between the two varieties, viz. : the one figured by Morton in his Synopsis, 

 pi. 15, fig. 9, and the pi. 4, figs. 1 and 2. 



I do not wonder that Prof. Marcou should have maintained the difference 

 between G. Pitcherii and G. Tucumcarii as he understood them, but the key 

 to the difficulty is this : G. Tucumcarii is the typical form of G. Pitcherii, 

 while G. Pitcherii, Marcou, is G. navis. This can be proven to any person who 

 will take the trouble of investigating the subject." 



Mr. Lea read a portion of a letter from Dr. Lewis, of Mohawk, New York, 

 giving an account of a very sudden and remarkable fall of temperature experi- 

 enced at that place, on the 7th of February last. The diagram exhibited was 

 an exact copy of the one made at the time, by the self- registering thermometer 

 devised by Dr. Lewis, and to which the attention of the Academy had been 

 oalled by Mr. Lea at a previous meeting. 



[Feb. 



