THE NAUTILI s. 115 



.4. Lip expanded or flaring. 



Zaplagius Pils., type D. navicula (=0tostomv,s Martens not 



Beck & Gray ; Navicttfu Spix not Blainv.). 

 Semielavsaria Pfr., type D. semiclausus. 



Drymteug s. str., types I), xanthostoma and hygrohylseus Orb. 

 Neopetneus Mts., type D. altoperuvianus. 



B. Lip simple, arcuate. 



Mesembrinus Alb., type D. virgulatus Fer. 

 Eudioptus Alb., type D. pseudosuccineus. 



('. Apical sculpture not distinctly grated. 



Leiustracus Alb., type D. v Hiatus (not Liostraca Burm.). 



The genus Dryuueus is represented within our limits by D. serper- 

 astrus in Texas, belonging to the restricted section Diijmmis, and in 

 Florida D. dormani and marielinut represent a section perhaps re- 

 quiring a new name. D.multilineatiis belongs to Mesembrinus. 



A certain number of Brazilian and Venezuelan forms, of which 

 D. vittatus, the type of Albers' group Leiostracus, is an example, 

 have superficial vermiculate wrinkles on the upper portion, exces- 

 sively fine, often indistinct, spirals on the lower portion of the second 

 apical whorl. This is quite different from the usual evenly grated 

 sculpture. It is often very indistinct. 



THE SIZE OF MUSSELS. 



BY W. S. STRODK, M. D., LEWI8TOWN, ILL. 



Some time since, in conversation with an aged naturalist, I in- 

 formed him that I had found a valve of Unio alatus Say, in Spoon 

 River, 111., that was nine inches long. He expressed surprise and 

 said that he never saw a mussel of any kind over six inches in 

 length, and, old as he was, he would walk five miles and go into 

 water up to his neck to get a specimen above that size. Feeling a 

 little taken back by his assertion, I determined to go home and make 

 some measurements of my largest species of Spoon River Uniones. 

 I was certain that I had several varieties that were above six inches 

 in length. The following is the result of my measurements: 



U. anodontoldes Lea, length 7 in., circumference 9 in. 



U. ligamentinus Lam., length 7 in., circumference 10'. in. 



