I? 



156 THE NAIADES OF MISSOURI 



Lasmonos leptodon? (Rafinesque). 

 Not Figured. 



1820 — Unio (Leptodea) leptodon Rafinesque, Ann. Gen. Sci. Phys. 

 Brux., p. 295, PI- LXXX. 



1829 — Symphynota tenuissima Lea, Tr. Am. Phil. Soc, III, p. 435, 

 PI. XI, Fig. 21. 



This species is listed here on the strength of reports of its 

 occurrence in the Mississippi and Neosho Rivers of this State. 

 From a shell, (measuring 58x31x14mm.), received from Michigan 

 through exchange, the author is able to make comparisons and thus 

 concur with the general assumption that it should group under 

 Lasmonos. However, superficial observations would group it 

 near Lastena ohiensis, but presence of hinge teeth, although not 

 well developed, and also different beak sculpture would sufficiently 

 separate it. Surety the "clear water streams" of South Missouri 

 may also yield specimens of this species since the same rivers that 

 reach up into Missouri are reported to bear it in Arkansas. Scam- 

 mon (1906, pp. 304 and 305) reports it for Kansas and Simpson 

 describes its general range for the upper Mississippi drainage 

 south to the Tennessee River and for Southern Michigan.^ 



Genus Proptera Rafinesque. 



1819 — Proptera Rafinesque, Monog. An. Gen. Sci. Phys. Brux.; — 1900b, 

 Simpson, Pr. U. S. Nat. Mus., XXII, p. 566, (as sub genus) ; 1912b, Ortmann, 

 An. Car. Mus., VIII, p. 332. 



(Type, Unio alaius Say) 



Animal Characters : — Branchial opening with dense papillae ; 

 anal crenulated; supra-anal small, moderately closely connected 

 to anal; inner laminae entirely connected to visceral mass; palpi 

 only slightly antero-dorsad ; marsupia reniform occupying pos- 

 terior part of outer gills, consisting of several ovisacs; conglu- 

 tinates not solid, broken; glochidium ax-head or celt-shape, 

 usually armed with two spines at each corner of ventral edge of 

 each valve; mantle border antero-ventrad to branchial opening 

 slightly lamellar with crenulations only. 



Shell Characters: — Shell subelliptic or subovate, solid to 

 thin, strongly alated post-dorsad; disk smooth; hinge fairly well 



' The presence of L. leptodon in Missouri need not be so questionable 

 now because of A. A. Hinkley's recent report of it in the James River at 

 Galena this State. (Dec. 23, 1915. Pr. U. S. Nat. Mus., Vol. 49. p. 588 ) 



