INTRODUCTION. 



53 



dccurrent on the whorl obliquely and with a very small 

 umbilicus. The name means half margin. 



"Hemiloma ovata. Ovate, very obtuse, smooth, six spires, 

 breadth two thirds of the length. Found near Lexington 

 in a nearly fossil state ; whitish, length three sixteenths of 

 an inch. 



In the same paper lie also describes a species of 

 Limax, viz. : 



"Limax gracilis. Body slender, head and lower tentacula 

 fulvous, neck gray, upper tentacula brownish, mantle dark 

 fulvous, back smooth brown, beneath dirty white ; tail brown, 

 obtuse above, mucronate and acute beneath ; probably a real 

 Limax. Yet it has the two long tentacula inserted above the 

 neck, while the small ones are terminal and all slightly club- 

 shaped. It may, perhaps, form a sub-genus Deroceras. 

 Length over one inch. Kentucky, in the woods. 



The shell upon which the genus Hemilonia was found- 

 ed has not been recognized ; it was probably a fossil. 

 There is reason to beheve, that Philomycus and Eumelus 

 origmated in the defective and careless observation of 

 M. Rafinesque. Certain it is, that no other observer 

 has yet found naked slugs with the four tentacles in one 

 row and nearly equal, with the two long ones inserted 

 above the neck, or without a more or less developed 

 mantle. A hasty examination of small individuals of 

 the animal, which in this work is included in a genus for 

 which the author has proposed the name of Tebennopho- 

 rus, might readily deceive any one who did not suspect 

 their peculiar characteristics, as the mantle is often so 



