806 PROCEEDINGS OF THE NATIONAL MUSEUM. 



(ENDOBRANCHI.^.) 



Male and female shells alike, with beak sculpture radial or zigzag- 

 radial; marsupium occupyiug the inner gills only. 



(ROSANORHAMPHUS.) 

 Beak sculpture zigzag-radial. 



Genus NODULARIA Conrad, 18BS. 

 (Type, r^iio douglasicn Gray.') 

 Nodularia Conrad, Pr. Ac. N. Sci. Pliila., 1853, p. 268. 



Shell elliptical to elongated, pointed behind about midway up from 

 the base, the post-basal part produced; beak sculpture variable, irregu- 

 larly zigzag-radial, often breaking into nodules, and extending in many 

 cases over a part or all of the disk; right valve with two usually com- 

 pressed pseudocardinals, one above the other, the lower the more ele- 

 vated, separated by a parallel- sided socket, and having one lateral; 

 left valve with two compressed pseudocardinals, both in front of the 

 beaks, and two laterals ; cavity of the beaks moderate, not compressed, 

 anterior muscle scars deep, posterior shallow, nacre Avhite. 



Animal (of N'. japanensis and ¥. ceqtiitoria) having the inner gills 

 alone filled throughout their entire length with ova, forming a pad-like 

 marsupium, united to the abdominal sac or free from it. 



Section LANCEOLARIA Conrad, 1853, 

 (Type, Unio f/raijanus Lea.) 



Shell ensiform, solid, with a distinct, pinched-up posterior ridge, 

 rounded in front, the posterior end sharp and generally turned a little 

 to the right or left; beaks low, their sculpture nodulous, zigzag, often 

 extending more or less over the surface; pseudocardinals rather 

 stumpy, ragged, striate above, smooth below; anterior muscle scars 

 distinct, the upper round, very deep, appearing as if bored out. 



Animal unknown. 



t NODULARIA GRAYANA Lea. 



* Unio grayanus Lea, Tr. Am. PbiL Soc., V, 1834, p. 66, pi. ix, fig. 26; Obs., I, 

 1834, p. 178, pi. IX, fig. 26.— -Reeve, Couch. Syst., I, 1841, p. 118, pL 

 Lxxxviii, fig. 4.--*Hanley, Test. Moll., 1842, p. 177; Biv. Shells, 1843, 

 p. 177, pi. XXIV, fig. 5. — ""CATLOwand Reeve, Conch. Nom., 1845, p. 59. — 

 *KusTER, Conch. Cab. Unio, 1856, p. 167, pi. XLVrii, fig. 5. — * H. and A. 



1 A large genns of generally rather small species, very abundant in individuals, 

 and distributed from the Amoor River throughout the mainland of all southeastern 

 Asia and all of Africa except the region bordering on the Mediterranean. Some of 

 the African species are so close to Asiatic forms of the ca'riileus group that they can 

 hardly be separated specifically. 



