12 AMERICAN JOURNAL 



Mr. Morse commences his paper by stating that since the 

 publication of Mighels' Catalogue, the number of terrestrial 

 and fluviatile mollusca, known to inhabit the State, has nearly 

 doubled. In studying them, he has been continually on his 

 guard not to rely too much on a single feature, but to consider 

 impartially all parts together. The interpretation of the 

 natural subdivisions which exist in these animals, will require 

 a deeper and more philosophical method of study, embracing 

 their complete embryology and anatomy, "and then whatever 

 may be revealed by such work, will, I believe, be as character- 

 istically stamped on the shell as on the habits and economy of 

 the animal." 



In the Ilelicidse, Mr. Morse detects three different types of 

 lingual dentition, and remarks that the three sub-families 

 founded on them, are alike distinguishable, from the "character 

 of the shell ; the external appearance of the animal, and the 

 general size of the species." 



" Taking the number of lingual plates in a row, from five 

 different species in each group from Pupinse upwards, and 

 averaging this number for each group, we have the following 

 result : — 



LIMACID^, including PHILOMYCENIDiE, 94. 

 HELICINiE, 73. 

 HELICELLIN^, 42. 

 VALLONIN^, 26. 

 PUPIN^, 24." 

 Tehennophorus dorsalis, Binney, is made a new genus PalU- 

 fera, characterised by arcuate buccal plate with seven promi- 

 nent ribs, crenulating its cutting edge. Central plate of tongue 

 tridentate, laterals bidentate, uncini denticulated. 



Sub-family Helicinse embraces the large species, such as 

 alholahris, Sayii, &c. 



Anguispira is proposed as a generic name for H. alternata^ 



Helicellinse embraces the thin diaphanous Helices like cellaria 

 electrina, ko,. ; with these is described a new species, H. Bin- 

 neyana, Morse. Differs from electrina in color, being nearly 

 white, with a greenish tinge, and is one-third smaller. 



a. exigva and H. minuscula form the new genus Pseudohya- 

 lina. "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 num- 

 ber. In Hyalina the shell is smooth and polished ; in this the 

 shells are either ribbed or striated." The buccal plate also 

 differs in form. 



Striatura ferrea is the type of a new genus and species, the 

 former " based upon peculiarities of dentition, as seen in the 

 enormous central plate and the channelled buccal lamina." 



