NATURAL SCIENCES OF PHILADELPHIA. 53 



Unio bulloides, Lea, Rio Plata, S. Am. 

 " atratus, (Niaa, Swain.) Chili. 

 " Araucanus, Philippi, Chili. 

 " piceus, Lea, Uruguay, S. Am. 



Cardinal and lateral teeth double in both valves. 

 Unto phaselus, Lea, Siam. 

 " scobinatus, Lea, Siam. 



Lateral tooth double in the right valve only. 

 Unto heterodon, Lea, Penn. 



Lateral tooth double in both valves. 

 Unio nucleus, Lea, Siam. 



Lateral tooth treble in the left, and double in the right valve. 

 Unio eximius, Siam. 



Cardinal tooth treble in the right valve. 

 Unio funebralis, Lea, Uruguay River, S. Am. 



Cardinal tooth treble in both valves, and lateral tooth treble in the right, and double 



in the left valve. 

 Unio trifidus, Lea, Buenos Ayres, S. Am. 



It is not pretended that the last table is entirely complete. The object is ac- 

 complished to shew that the teeth of different species vary normally, and that 

 individuals of the species vary abnormally. 



As regards the genus Triquetra, Klein, (ffyria, Lamark,) which has cardinal 

 and lateral teeth in both valves, so far as observed the lateral tooth in the 

 left valve is double, and in the right single. 



The cardinal tooth in both valves is usually lamellar and multiplied, and 

 articulate closely. In some cases it is much longer than in others of the 

 same species. In one specimen of T. subviridis, Klein, in Mr. Lea's cabinet, the 

 the cardinal tooth is almost the same length of the lateral tooth ; and in two 

 specimens both teeth have transverse striae like Prisodon, Schum. (Castalia, 

 Lam.) which of course is an aberrant form. The Triquetra contorta, Lea, is an 

 aberrant species, the cardinal teeth in both valves being obtusely conical and 

 double in both valves. I have never met with any abnormal form of teeth in 

 any of the species of Triquetra, but so few specimens get into the cabinets that 

 if they do exist none have yet been detected. 



The genus Prisodon, the teeth of which are so nearly the same as those of 

 Unio as to induce M. Deshayes to put it in that genus, are almost identical 

 with some of the species, except in character of transverse parallel striae ; 

 and even this characteristic of the genus is absent in some of Mr. Lea's 

 specimens of truncatus, Schum., (ambigua, Lam.) If, however, the lobes of 

 the mantle are united behind so as to form two tubes, there would be no pro- 

 priety in placing it with the Uniones, as the mantle is never united in that part 

 in them. 



Prof. R. E. Rogers made some remarks on the debitumenization of coal, 

 and also communicated tbe following facts having reference to the propaga- 

 tion of concussion from rock-blasting to strata at a distance, as exemplified 

 in the effect upon the water of wells. 



A well, sixty feet in depth, with the water rising within ten feet of the sur- 

 face, had, previous' to the occurrence, been yielding a large supply of water 

 to an extensive factory, when, immediately upon the discharge of a heavy 

 blast in a stone quarry about four hundred yards distant, the water began to 

 fall, and soon altogether disappeared. 



I860.] 



