NO. 1205. SYNOPSIS OF THE NAIADES SIMPSON. 597 



tNEPHRONAIAS PLICATULUS Charpentier in Kuster. 



* Unio plicatulua CHARPENTIER in KUSTER, Conch. Cab. Unio, 1856, p. 154, pi. 



XLIV, fig. 4. *FISCHER and CROSSE, Miss. Sci., Pt. 1. II, 1894, p. 598. 



Mexico. 



tNEPHRONAIAS RAVISTELLUS Morelet. 



* Unioravistellus MORELET, Test. Noviss., No. 1,1849, p. 29. *KUSTER, Conch. Cab. 



Uuio, 1856, pi. XLII, fig. 6. *B. H. WRIGHT, Check List, 1888. *P/ETEL, 

 Conch. Sam., Ill, 1890, p. 165. *FISCHER and CROSSE, Miss. Sci., Pt. 7, II, 

 1894, p. 609, pi. LXI, figs. 4, 5, and 5a. 

 *Margaron ( Unio) ravistellus LEA, Syn., 1870, p. 40. 



Guatemala. 



tNEPHRONAIAS VELLICATUS Reeve. 



* Unio vellicatm REEVE, Conch. Icon., XVI, 1865, pi. xxn, fig. 103. "B. H.WRIGHT, 



Check List, 1888. *P^5TEL, Couch. Sam., Ill, 1890, p. 171. *Fl8CHER and 

 CROSSE, Miss. Sci., Pt. 7, II, 1894, p. 610. 



Guatemala. 



NEPHRONAIAS MELLEUS Lea. 



* Unio melleus LEA, Pr. Ac. N. Sci. Phila., XI, 1859, p. 152; Ml. Ac. N. Sci. Phila., 



IV, 1860, p. 250, pi. xxxvm, fig. 129; *Obs. VII, 1860, p. 68, pi. xxxvin, tig. 

 129. *REEVE, Conch. Icon., XVI, 1865, pi. xxi, fig. 92. *P^ETEL, Conch. 

 Sam.,III, 1890, p. 158. 

 *Margaron ( Unio) melleus LEA, Syn., 1870, p. 35. l 



Mexico or Central America, no doubt. 



GENUS GLEBULA Conrad 1853. 



(Type, Unio rotundata Lamarck.) 2 

 Glebula CONRAD, Pr. Ac. N. Sci. Phila., 1853, p. 268. 



Shell solid, much inflated, short elliptical, bluntly pointed and slightly 

 biangulate behind, with a low, posterior ridge; female shell swollen at 

 post base; beaks compressed, the sculpture not seen; epidermis brown- 

 ish, clothlike; pseudocardinals divided into irregularly radiating, gran- 

 ular lamina, sometimes to the number of a dozen or more in each valve; 

 hinge plate reduced to a mere rounded line behind the pseudocardi- 

 nals; laterals short, remote, anterior adductor scars deep, smooth; 

 there is in each valve only a single, large, semicircular posterior scar 



1 1 am not certain just where this and the preceding species should he placed. 

 This remark can be applied to a number of other forms placed in this genus. 



2 1 have examined a number of animals of the only species of this curious genus, 

 but regret that they were badly decayed, and that none were gravid. In one speci- 

 men several ovisacs were distended with gas, and these were separated by a deep 

 sulcus. This fact, the union of the inner gills with the abdominal sac, and the post- 

 basal swelling seen on some shells incline me to believe that it is a highly organized 

 species. 



