T II K FAMILY OF UXIOXID.E. 



XXI 



AGASSIZ'S DIVISION OF UXIOXID.E.' 



Palpi. 



'Unio. ff^'r. Emended. 

 D complaoatus. Lea. 



Enrynea. 4 Raf. Emen- 

 ded. 



I'. pra?longns. Bar, 

 nasutus. Say. 



I, impsilis.* Raf. 

 Emended. 

 L". radiatus. Lam. 



Metaptera. 6 

 Emended. 

 I". status 



Raf. 

 , Say.' 



Omplanaria. Swain, United along the pos- 

 Emended. tenor edge % of 



Alas:rugosa. Bar.* the length. 



Ma rga ri tana. Sch u m. 

 Alas, arcuata. Bar. 



Alasmodonta. Say. 



Emended. 

 Alas, niarginata. 

 Smj. 

 Strophitus. Raf. 

 Emended. 

 An uudulata. 

 Say." 



Anodonta " Brug. 

 An. Benedictensis. 

 Lea. 



Mantle.. 



Fringed at both siphonal open- 

 ings. 



Fringed at posterior half of 

 ventral edge, and at branch. 

 and anal siphons. 



Fringed at both siphonal open- 

 ings, having fleshy thicken- 

 ings and processes at post, 

 ventral edge. 



Broad expansion upwards. Su- 

 peranal opening long. Both 

 openings fringed. 



Superanal opening long. Both 

 siphonal openings fringed. 



Anal opening of mantle not 

 fringed ; branchial is fringed. 



Branchial opening fringed. 

 Anal opening large, not 

 fringed. 



Anal opening not fringed. 



Anal opening not frirged. 



Gills. 

 ■Free from abdominal sack, 

 post, extremity attached to 

 mantle. Eggs filling extent 

 of outer gill. 



Attached to abdom'l sack. Xo 

 opening between pedal and 

 upper gill cavities. Eggs in 

 posterior part of outer gill. 



Attached. Eggs in posterior 

 part of outer gill. 



Attached. Eggs in posterior 

 part of gill. 



Free. United to the mantle to 

 its margin. Outer gill filled 

 entirely with eggs. 



Free from abdominal sack. 



Post, extrem. not united to 



mantle. 

 Attached to abdominal sack :' 



attached also to mantle to the 



extremity. 



Attached. Eggs received in the 

 whole extent of outer gill. 



Free. Eggs throughout the gill. 



/' ■/ 



1 Shells of Neio England, ISol, by Wm, Stimpson. 



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



1 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. 



* Rafiuesque gives no anatomy. This is his generic description of the genus; "Valves very transverse or very large. Axis almost lateral." 

 s Rat. says: "Mollusc like that of Unio, hut has apparent short syphons." 



6 Raf. says: "Mollusc like that of Unio." 



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



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



8 Alas, margiuata. Six specimens from Mohawk River were all more or less open ; some a mere point at posterior end of the foot! See U. Novi- 

 El i m ; ; Obs, x. ■'>"». Some attached, some not. 



10 Prof. A. says; "Anal opening not fringed, but it is very minutely fringed." 



11 An Ferussaciana, Lea, has papilla? on the anal opening. 

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

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

 Uuio Forsheyi, Lea, has no papilla?. 

 Unio Tappauianus, Lea, has no papilla?, but has slight crenulations. 



Unio laevissimus, Lea, has no papilla* on the anal opening. 

 Unio Blandianus, Lea, has no papilla? on the anal opeuiug. 

 Unio Houstonensis, Lea, has no papillae. 

 Unio verrucosus, Bar. has no papilla. 



The 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 the opening or 

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

 "Gills attached to abdominal sac." 1 Another important character is the possession 



Shells of New England, by W. Stimpson, p. 13. 



