FRESH WATER MUSSEL SHELLS 131 
of the rate of growth of certain species, particularly for that period 
after the juvenile stages. Additionally, the present paper con- 
tributes further to a series of biometric studies of mussels in relation 
to their environment inaugurated by Ortmann, (16), continued by the 
writer, (3-8), and by Ball, (1), in a recent paper. 
II.—Listr or Species anp Source or MareriaL UseEp. 
The material studied consisted of juvenile and adult specimens of 
the following species, which are listed in conformance with the 
recent changes in the nomenclature of the Naiades sponsored by 
Ortmann and Walker, (17). The older name by which certain of 
them are known is indicated in parentheses. 
Fusconaja flava parvula (Grier). 
Amblema plicata (Say). 
Pleurobema coccineum pauperculum (Simpson). 
Elliptio dialatus sterkii (Grier). 
Lasmigona (Symphynota) costata eriganensis (Grier). 
Anodonta grandis footiana (Lea). 
Leptodea (Paraptera) fragilis (Raf.). 
Proptera alata (Say). ; 
- Anodontoides ferrussacianus subcylindraceus (Lea). 
10. Ligumia (Lampsilis) recta (Lam.). 
11. Lampsilis siliquoidea (Luteola) rosacea (DeKay). 
12. Lampsilis ovata canadensis (Lea). 
SYA STA SS 
The species listed represent well defined varieties of the parent 
Upper Mississippi species, (3,7). They were collected by Dr. A. E. 
Ortmann of the Carnegie Museum in Lake Erie over a number of 
years, (1903-07), for a study of this kind; and are now in the 
collection of the Museum. Most of them were obtained at Presque 
Isle Bay, but a smaller amount came from La Plaisance Bay and 
Cedar Point. I am indebted to Dr. Ortman for:the use of the 
material, as well as to the authorities of the Museum for the fullest 
use of its facilities. 
III.—Puysicat Conpirions aNp Tyre or Musser Fauna. 
The type of mussel fauna has already been admirably treated in 
papers by Walker, (18), and Ortmann, (15). These and the physical 
conditions concerned have already been discussed fully by the writer 
elsewhere; (7), the Jatter being ably given for Lake Erie by Jen- 
nings, (11). For sake of convenience, however, the outstanding 
points concerning the physical conditions are given in the following 
” 
