Pulmonifera of Maine. 15 



api^ear to be raised but are rather within the substance of tlie 

 periostraca. 



Buccal plate, (Fi(j. 28,) crescentic, tapering to a 

 point at each side, roundly projecting in the centre \ iiir ';!| 



of cutting edge, and correspondingly depressed on 

 posterior edge. ^ '0- -"' 



Lingual membrane 82-21-1-21, central plate broad and square, ■widening 

 posteriorly, tridentate, central denticle longer than plate, laterals four, long, 

 narrow, projecting at outer posterior corner, having one long and one short 

 denticle, uncini simple, long, recurved spines, those nearest laterals having on 

 then- outer side a small denticle. (PI. 6, Fig. 29.) 



Hyalina multidentata, Binney. {Fig. 30.) 



A few specimens only have been found in Cumberland and 

 Oxford Counties. 



Animal white with a blueish tinge, back mottled with black, 

 eyes scarcely visible. 



The periostraca exhibits no traces of longitudinal lines ; the 

 lines of accretion are very faint ; equidistant fun-ows radiate from 

 the suture as in H. indentata. 



Buccal plate, (Fig. 31,) crescentic, sides turning 

 sliglitly back, cutting edge nearly straight, faintly 

 notched. 



Lingual membrane 68-15-1-15, central plate broad, Fig. 31. 



flaring out posteriorly, tridentate, central denticle longer than plate, side denticles 

 very small ; laterals two, similar in shape having one long and one short denticle ; 

 imcini, long recurved hooks, first of the Uncini more like a modified lateral. 

 (PL 6, Fig. 32.) 



The peculiarities of the shell may form the type of a sub-genus, 

 though I prefer placing it at present Avith Hyalina. 



Pseudohyalina. not. gen. 



We unite under a distinct generic title the two following species. 

 They are closely connected with Hyalina by the aculeate uncini, 

 though the differences seen in the shell, peculiarities in the denti- 

 tion and buccal plate, I consider to warrant their separation. 

 In Hyalina the laterals comprise one-sixth or one-seventh of the 

 whole number of plates in a row, while in Pseudohyalina the 

 laterals comprise about one-third the number. In Hyalina the 

 shell is smooth and polished ; in this the shells are either ribbed 



