89 Notes on certain Terrestrial Mollusca, 



last, and perhaps the apicial, whorl. Jaw (tig. 3) arcuate, with 

 a slight median projection, distinctly, longitudinally costate, 

 the costse, 9-10 in number, flattened, their terminations scarcely 

 produced at the anterior or cutting margin, parallel with which 

 are a few fine stria 1 . 



In tin- jaw of the second specimen examined, the number of 

 c >stae was found to he L3, and the cutting margin very per- 

 ceptibly crenulated by .their extension. 



At first sight, under the microscope, the jaw of E. New- 

 combia/num appears to consist of a series of plates, the costse 

 formed by their overlapping edges ; and indeed Binney, 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 llattencd costae. 



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

 jaw of /;'. Newcombianum 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, " margira 

 swpero radicem rotundatam * mi/h ut< ." 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, hut on further 

 examination I satisfied myself thai it is only the more dense 

 condition of the buccal muscles. I may he wrong, hut do nol 

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

 like that in Succinea, which can l»e cleared as readily from the 

 integuments as the cutting plate it -elf." Morch, in the < 1 esc rip- 

 tion of his division ELasmognatha which embraces Succinea, 

 mentions the existence of a membranous attachment to the jaw 

 of Dryptus BlainviUeanus (Jour, de Conch, 7.391, L865), 

 hut it is of a eery different character to that observed in /*.'. 

 \. wcombianum. 



