THE NAUTILUS. 61 
tically in the sandy bottom with the body whorl only exposed. 
I do not know whether they buried themselves or the shifting 
sands did. 
The Unio complanatus collected varies greatly with the locality. 
Those from the Rahway River are cleaner than those from 
Notch Brook and are not so ventricose. The anterior end is 
more elongate than the brook form, and the sexes are hardly 
distinguishable. The Notch Brook females are much shorter 
than the males and more truncated, as the following measure- 
ments of the largest specimens show: 
Locality. 
| 
Sex. | Length. Breadth. Thickness. 
, 
Rahway River... 
Female.| 75 mm. | 388 mm. | 20 mm. 
Male. 70 mm. | 35 mm.| 18 mm. 
Great Notch Brook. 
| 
Male. | 72mm. | 38 mm.| 19 mm. 
| Female.! 63 mm. | 40 mm.| 19 mm. 
Having collected only in two localities this year I obtained 
the following species. From Branch Brook Park, Newark, 
Planorbis parvus and Planorbis antrosus. These species were 
found in shallow water near the shore. 
At Halcyon Park (Bloomfield) in a small pond, if it can be 
called such, I found large Planorbis trivolvis, the largest of which 
measures 25 mm.; also Pseudosuccinea columella and a species of 
Ancylus which I have not identified. I believe the shells in this 
pond came with the water-lilies that are growing there. 
