VOL. XIX.J PHILOSOPHICAL TRANSACTIONS. 17 1 



may convey the food roiintl, from whatever part it be in, to the mouth ; thus 

 supplying the place of a hand. As for the real, or properly so called, branchiae, 

 they are four in number, of a slightly yellowish colour, and elegantly striated 

 in a pectinated manner; they surround the large central muscle, and compre- 

 hend or lie upon the uterus and ovarium, or parts of generation. Near the 

 mouth or opening is a process with a doul)le orifice ; one of which must be con- 

 sidered as the termination of the female organ, and (if the animal be, as I sus- 

 pect, androgynous) the other must be supposed to afford a passage for the male 

 organ. To proceed to the liead of the animal : it is surrounded by reddish lips, 

 in the manner of the internal branchiaa, but they are very short. The head lies 

 inbedded in a large black meconium tending towards the left. Beneath which 

 is concealed the heart, which may be seen through the pellucid pericardium, 

 and is of a light reddish colour; the aorta is distributed over the branchiae; from 

 the meconium or black part before-mentioned proceeds the rectum, and going 

 over the pericardium is stretched towards the internal branchiae, and is con- 

 nected to the central muscle ; this central muscle is orbicular, white, and smooth 

 for a great part of its surface, where it adheres to the shell, but on the left side 

 is distinguished by another, whiter and lacerated muscle, and is still more strongly 

 attached to the shell. 



aaa, the mouth and head, fig. 2, pi. 4 ; bb, the deep black meconium ; c, the 

 heart, a'; it lies beneath its membrane; dd, the pericardium, or (perhaps) rhomboid 

 urinary bladder; eeeee, the rectum, ruiming over the pericardium ; ftfff, the large 

 central muscle; gg, the other lacerated muscle, strongly adhering to the shells ; 

 hhhh, the internal branchicc ; ii, the exit of the lengthened uterus, with its two 

 foramina ; kk, the upper whitish part of the uterus ; 111, the lower saffron-co- 

 loured part of the uterus ; mmmmm, the variegated border, or second reticular 

 muscle. 



A Letter from Mr. Halley at Chester, giving an Account of an extraordinary 

 Hail in those Parts, on the 2Q!h of April last. N^ '229, p. 5/0. 



The vapour that disposed the aqueous parts thus to congeal, came with a south- 

 west wind out of Carnarvonshire, [)assing near Snowdon with a horrid Ijlack 

 cloud, attended with frecjuent lightnings and thunder. I hear no further of it 

 westward than out of Denbighshire, where it left St. Asaph to the right, and 

 did much damage between it and the sea, breaking all the windows on the wea- 

 ther side, killing poultry, lambs, and a stout dog; and in the north part of 

 Flintshire several people had their heads broken, and were grievously bruised in 

 their bodies. From Flintshire it crossed over the arm of the sea that comes 

 up to Chester, and was only felt in Cheshire, at the very N. W. corner of the 



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