NO. 1342. ' SYNOPSL'^ OF THE ASTARTIDJi^DALL. 935 



World in the National Museum is exceptionally large, a fact iiju)!) 

 which the poHsibilit^y of a review of the species is dependent. In a 

 general way the species common to both hemispheres belong to tlie 

 circumpolar fauna; extremely few if any of the more southern species 

 are common to Europe and America. In a general way each fauna 

 has a set of species in which a given type is represented, but the repre- 

 sentatives of the type when compared are found to be similar rather 

 than specitically identical. Thus, the European .1. sxleata, co/npnssa, 

 and incrassata do not in my opinion occur at all in America, though 

 the Atlantic and Pacilic faunas have analogues which areprobablv due 

 to lining a particular similar niche in the environment rather than to 

 any close connection with the types of Europe referred to. 



The distinctions upon which the sul)ordinate groups of jUtarfi(he 

 are founded are chiefly the greater or less development of the hinge- 

 teeth and modifications of external sculpture. As the type of the 

 hinge formula does not change but merely submits to certain deduc- 

 tions from its possible total, it will be inferred that th(^ subgenera or 

 sections are not ver}' widely separated. 



The genus GoodaU/ojjs/'s Munier-Chalmas and De Raincourt, 1863, 

 is a synonym of KelJla. Pleslastarte Fischer, 1887, which has also 

 been referred to this family, may perhaps be more suitably placed in 

 the Cyrenidse^'ii not a nepionic shell. Prsecrmiu Stoliczka, 1871, and 

 PacJiytypus Munier-Chalmas, 1887, I have not been able to examine; 

 l)oth are fossils. Parisiella Cossmann, 1887, from the figures, mav be 

 a member of this family and related to Microstagon. It is from the 

 French Eocene. Paleozoic forms referred to Astarte are dubiously 

 pertinent. 



SUBDIVISIONS OF THE FAMILY. 



Genus LIRODISCUS Conrad, 1869. 



Shell solid, inequilateral, equivalve, the nepionic valves flat, usually 

 concentricalh^ ridged, the later portion of the disk more convex; liga- 

 ment normal, external; residium separate, situated between the l)eaks, 

 external, but with its base encroaching on the umbonal ends of the 



1- , . , .. , LOl.1010.01 ,, , ., , . , , , ,.. 



cardinals; dental formula rk) oiqi lO ' *^® ^^*^ anterior lateral often 



indistinct; inner margins crenate; adductor scars rounded with elevated 

 margins. 



Type Astarte tdlinoides Conrad, Claibornian Eocene. This genus 

 appears in the lowest Eocene and continues to be represented until the 

 Jacksonian. 



Genus ASTARTE Sowerby, 1816. 



Synonyms: Tridonta Schumacher, 1817; Crassiua Lamarck, 1818; 

 Trlodonta Agassiz, 184:7; Nicania Leach, 1819; Gonllia Stoliczka, 

 1871; Crassinella Bayle, 1879, not Guppy, 1874; Weoo'asmia F\sc\iqi\ 



