18 



Observations on the Terrestrial 



well rounded, very large, spire slightly elevated. Suture distinct, 

 and deeply channeled near the apex. TJmbilicus small, thoiigh 

 abrupt, and exhibiting all the volutions. Diameter .10 inch, axis 

 .05 inch. Periostraca minutely marked with fine revolving lines, 

 and lines of increase, which reticulate the whole surface. {Plate 

 2, Fig. 10.) 



Buccal plate, (FUj. 89 J slightly 

 bent, tapering at sides ; deeply 

 channeled and indented in middle 

 of cutting edge. 

 Lingual membrane 39-20-1-20, 

 Fig. 39. central plate enormous, equal in 



size to two laterals, nearly twice as broad as long, outer posterior corners 

 projecting outward and backward, central denticle longer than plate, very thick, 

 smaller denticle on each side at base of central denticle, laterals two, bidentate, 

 first lateral small, broader than long, very irregular in shape, having at its 

 posterior portion a slight transverse projection, denticles small ; central lateral 

 longer than broad, with one long and one short denticle, uncini aculeate. (Plate 

 7, Fig. 40.J) 



It resembles the young of Hyalina indentata very much, and 

 for a long time I have mistaken it for the young of that shell. 

 Rev. E. C. Bolles frequently called my attention to it, as he could 

 not with propriety refer it to H. indentata. On subjecting a 

 specimen to the microscope, its specific value was at once apparent 

 in the marking of the periostraca, which in H. indentata is perfectly 

 smooth, exhibiting only the faintest revolving lines; H. feiTca 

 lacks also the impressed radiating lines so characteristic of H. 

 indentata. The apex is marked with distinct revolving lines, the 

 open umbilicus is constant, and it is not half as large as an adult 

 indentata ; finally the dead color alone is sufficient to distinguish 

 it from the latter shell. Found in damp localities. 



Striatura milium, Morse. {FigAl.) 



Appears to be generally distributed 

 throughout the State, and occurs also in 

 several places in Massachusetts. Though 

 met with in almost every place, where 

 the smaller species of jiulmonates are Fig. 41. 



sought, but one or two specimens are ever found at a time j this 



