908 NEW YORK STATE MUSEUM 



LAMELLIBRABTCHIATA 



Genus nucula Lamarck 



Nucula lirata Conrad, mut. pygmaea nov. 



Plate 1, fig. 14, 15 



The form is triangular ovate, rounded more abruptly in front 

 than behind. The beaks are near the front, and the valves gib- 

 bous. The length is about one fourth greater than the hight. The 

 individual figured measures 2 mm in length, 1% mm in hight and 

 1 mm in thickness. The pyrite form differs from the ancestral 

 in the beaks being situated nearer the front, and in less gib- 

 bosity. Otherwise the resemblance is close, except that the 

 dwarf is about one tenth the size of a normal N. lirata. 



Localities. At the Livonia salt shaft and Greigsville. Total 

 specimens 5. 



Nucula corbuliformis Hall, mut. pygmaea nov. 



Plate 1, fig. 10, 11 



This form is an almost exact miniature of the normal N. cor- 

 buliformis. The specimens are internal casts showing the 

 impress of the teeth, pallial line, adductor muscles, and the 

 small muscles in the umbonal region. A specimen measures 

 10 mm in length, 7% mm in hight and 5 mm in thickness; this 

 being about one half the normal size. 



Localities. At Canandaigua lake and at Livonia. 



Nucula varicosa Hall, mut. pygmaea nov. 



Plate 2, fig. 3, 4 



The form is triangular ovate in outline, the anterior end be- 

 ing abruptly rounded, the posterior almost truncate. The beaks 

 are nearly at the anterior end and approach each other closely. 

 The valves are strongly gibbous, their surface showing slight 

 wrinkles, apparently indicating varices on the exterior of the 

 shell. The teeth have left no impress on the cast. The type is 

 2*4= mm in length, l 2 / 3 mm in length and 1% nana in thickness. 

 They approximate N. varicosa closely except in size, being 

 about one sixth the diameter. 



Localities. Moscow, near the Delaware, Lackawanna and 

 Western Railroad and on Little Beard's creek. Total speci- 

 mens 2. 



