NO. 1205. SYNOPSIS OF THE NAIADES SIMPSON. 809 



f NODULARIA DOUGLASI-flE var. NIPPONENSIS von Martens.' 



* Unio nipponensia VON MARTENS, S. B. Nat. Fr., 1877, p. 119. *KOBELT, Abh. 



Senck. Nat. Gea., XI, 1879, p. 422, pi. xn, fig. 3. "P/KTEL, Conch. Sam , III, 

 1890, p. 161. * VON IHERING, Abh. Senck. Nat. Gea., XVIII, 1893, p. 160. 



China; Amurland; Japan. 



| NODULARIA DORRI Wattebled. 



* Unio dorri WATTEBLED -Tl. de Conch., XXXIV, 1886, p. 71, pi. v, fig. 5. *P/KTEL, 



Conch. Sam., Ill, 1890, p. 151. 



Cochin China; Anam; Mekong river. 



NODULARIA DIGITIFORMIS Sowerby. 



* Unio digiti/ormis SOWERBY, Conch. Icon., XVI, 1868, pi. i-xv, fig. 333. *P,KTEL, 



Conch. Sam., Ill, 1890, p. 150. 2 



India. 



(Group of Nodnlaria japnnensis.} 



Shell solid, elliptical, subrhoniboid or oval, biangulate, rounded or 

 pointed behind and often produced at the posterior base; posterior 

 ridge low or scarcely developed; beaks moderately fullj sculpture zig- 

 zag radial; surface of the valves concentrically striate or more or less 

 covered with corrugated chevron-shaped sculpture which often becomes 

 somewhat nodulous; epidermis greenish and sometimes rayed in young 

 shells, becoming brown or blackish when adult. 



Animal having the inner gills wider than the outer in front, equal 

 behinl, free from the abdominal sac throughout, united to the mantle 

 to the extreme posterior point; palpi rather large, long; mantle double 

 on the border and toothed below; branchial opening large, with well- 

 developed, brown papillre; anal opening large, with small tubercular 

 papilla? on its inner edge, covered with wart-like papilla 1 inside; super- 

 anal opening not closed below. 3 



t NODULARIA JAPANENSIS Lea. 



* Unio japanensis LKA, Pr. Ac. N. Sci. Phila., Ill, 1859, p. 153; * Jl. Ac. N. Sci., 



Phila., IV, 1860, p. 244, pi. xxxvi, fig. 123; *Obs.,VII, 1860, p. 62, pi. xxxvi, fig. 

 123.* VON MARTENS, Mai. Bl., VII, 1861, p. 55.* KUSTER, Conch. Cab. Unio, 

 1862, p. 227, pi. xcin, fig. 4.* SOWERBY, Conch. Icon., XVI,1868,pl. LXXX, fig. 

 420. *P^F.TEL, Conch. Sam., Ill, 1890, p. 155. * vox IHERING, Abh. Senck. 

 Nat. Ges., XVIII, 1893, p. 157. 

 "Margaron ( Unio) japanensis LEA, Syu.,1870, p. 31. 



1 Most of the Japanese forms of this species are smaller than those found on the 

 mainland, though I have seen nothing that exactly agrees with Robert's figure. The 

 ordinary form of douglasice is found also in Japan. 



2 This seems to stand between this group and that of N. grayanus. 



3 The shells of some of the species of this group are very different from the normal 

 Nodularia, being covered with roughish epidermis and apparently lacking sculpture. 

 Others, however, show occasional sculpture, and the young shells have the green 

 epidermis characteristic of the group. 



