THE FAMILY OF UNIOKID.^. 



AGASSIZ'S DIVISION OF UNIONIDyE.* 



110. Hetz. Emended. 

 U. complanatus. Lea. 



Eiiryaea.* Raf. Emen-^ 

 ded. 

 U. prffllongus. Bar. 

 nasutiis. Say. 



Lampsilis.s Raf. \ 



Emeaded. 

 U. radiatus. Lam. 



Metaptera.^ Raf. 

 Emeuded. 

 U. alatus. Say."^ 



Complanaria. Swain. 

 Emended. 

 Alas, i-ngosa. Bar.^ 



Mar^'aritaua. Schum. 

 Alas, arcuata. Bar. 



Alasmodonta. Say. 

 Emended. 



Say. 

 StrophUu.s. Raf. 

 Emended. 

 Aa. uodulata. 

 Say.^'^ 



Anodonta n Brug. 

 An. Benedictensis. 

 Lea. 



United along the pos' 

 terior edge % o: 

 the length. 



Mantle.. 

 Fringed at both siphonal open- 



Gills, 

 Free from abdominal sack, 

 ings. post, extremity attached to 



mantle. Eggs filling extent 

 of outer gill. 



Fringed at posterior half of Attached to abdom'l sack. Tfo 



entral edge, and at branch, 

 nd anal siphons. 



inged at both siphonal opeu- 

 ngs, having fleshy thicken- 

 ngs acd processes at post, 

 ventral edge. 



Broad expansion upwards. Su- 

 peraual opening long. Both 

 openings fringed. 



Superanal opening long. Both 

 siphonal openings fringed. 



opening between pedal ani 

 upper gill cavities. Eggs i: 

 posterior part of outer gill. 



Attached. Eggs in posterio 

 part of outer gill. 



Attached. Eggs 

 part of gill. 



^ee. United to the mantle to 

 its margin. Outer gill filled 

 entirely with eggs. 



Anal opening of mantle not 



Free from abdominal sack. 



fringed ; branchial is fringed. 



Post, extrem. not united to 





mantle. 



Branchial opening fringed. 



Attached to abdominal sack ;" 



Anal opening large, not 



attached also to mantle to the 



fringed. 



extremity. 



Anal opening not frii 



Anal opening not frirged. 



Attached. Eggs received in the 

 whole extent of outer gill. 



Free. Eggs throughout the gill. 



ry transfers 



■ very large. Ax 



nost later; 



1 Shells of New England^ 1S.51, by Wm. Slimpson. 



2 U. infucatus, Con. seems in the alcoholic specimen not to have the anal opening fringed. Also, Unio metanever, Raf. and lacrymosus, Lea. 



^ U. multiplicatus. Out of five large ones, three were attached the whole length, and two open for a short distance. U. Berlandierii had four out 

 of five attached; the fifth slightly open. 



* Ritfinesque gives no anatomy. This is his generic description of the genus: " Valv 



* Raf. says: "Mollusc like that of l/nio, but has apparent short syphons." 

 " Kaf says: "Mollusc like that of Unio.'" 



' There is no essential difference in the diagnoses of these three genera. 

 ^ Alas, rugosa. Bar. has not the anal opening fringed. 

 " Alas, marginata. Six specimens from Muhawk River were all more or less open ; some a : 



Eboraci ; Obs. x. 5o. Some attached, some not. 



*** Prof. A. says: "Anal opening not fringed, but it is very minutely fringed." 

 " An. Ferussaciana, Lea, has papillae on the anal opening. Unio Iffivissim 



Unio pustulosus, Lea, has no papilla or crenulations on the anal opening. Unio Blandian 

 Unio Kleinianus, Lea, has no papilla, but has slight crenulations. Unio Housto 



Unio Forsheyi, Lea, has no papillse. Unio verr 



Unio Tappanianus, Lea, has no papillae, but has slight crenulations. 



i point at posterior end of the foot! See U. Novi- 



Lea, has no papilla on the anal opening. 

 Lea, has no papillae on the anal opening. 



a, has no papilla. 

 Bar. has no papilla. 



Tlie very uncertain characters by which Prof. Agassiz proposed to divide this 

 Family induced me to make notes of many species in which the anatomy did not 

 seem to me to accord with his views. His principal character is tlie opening or 

 closing of the pedal and upper gill cavities. " Grills free from abdominal sac," and 

 "Gills attached to abdominal sac."^ Another important character is the possession 



^ Shells of New Englaucl, by W. Stimi^son, p. 13. 



