with bescrvptions of New Species. 7 



At first sight, under the microscope, the jaw of J^. JVew- 

 comhianum appears to consist of a series of plates, the costse 

 formed bj their overlapping edges ■ and indeed Binnej, after 

 carefully examining it, justly remarked that the structure of 

 the jaw of other species may have been incorrectly described. 

 The jaw is, in fact, so thickened in various parts and with such 

 general regularity, as to give the impression that it is composed 

 of separate plates, while portions have additional thickness, 

 producing what I have called flattened costse. 



At or near to the central part of the superior margin of the 

 jaw of E. Neioeom'bianuin there is an attachment, which I 

 supposed to be similar in character to that mentioned by 

 Crosse and Fischer in their description of the genus, ^'"marghu 

 supero radicem rotundatam emittenteP To this appendage I 

 directed the attention of Morse, who wrote as follows : " I 

 noticed at the outset the process to which you refer, and the 

 jaw of Succinea immediately occurred to me, but on further 

 examination I satisfied myself that it is only the more dense 

 condition of the buccal muscles. I may be wrong, but do not 

 see any evidence of a process separate from the muscles, — ^not 

 like that in Succinea^ which can be cleared as readily from the 

 integuments as the cutting plate itself.'' Morch, in the descrip- 

 tion of his division Elasmognatlia which embraces Succinea^ 

 mentions the existence of a memhranoiis attachment to the jaw 

 of Dryptus Blainvilleaniis {Jour, de Conch, v. 391, 1865)^ 

 but it is of a very difi'erent character to that observed in M, 

 KeWcomljianiim . 



The teeth of E. J^eiccomhianum (fig. 3) in arrangement and 

 form agree very closely with those oi Eucalodium., as described 

 by Crosse and Fischer, and the formula 32-1-32 x 126 is re- 

 markably similar. In my figure the median and adjoining 

 lateral teeth, and also the extreme lateral tooth (fig. 3, a.)^ are 

 shown. The teeth in general character may be compared Avitll 

 those of II. alteroiata Say {Morse ^ Terr. Pidmon. of Jfame^ 

 pi. 4, fig. U). 



