ORDER n ANOMALODESMACEA 



The recent families, Prasinii!<in MH\ ,V'//V/v /<//-, it' tln-ir validity 



Pra. 085. 

 Congeria subglolosn, I'artsch sp. Upper Miocene ; Inzersdorf, near Vienna. 



may find a place in this vicinity. Prasina and Berthelinia are reported from tin- 

 Tertiary. 



Order 2. ANOMALODESMACEA. Ball. 



Superfamily 1. ANATINACEA. Dall. 



Anomalodesmacea with V-shaped reticulate gills not secreting a, calcareous tube exterior 

 to the shell. 



This group is divisible into sections as follows : (a) Eusiphonia, with long siphons and 

 the lithodesma, when present, at the anterior end of the internal resilium, and external to 

 the mass of the resilium ; and (b) Adclosiphonia, with short siphons, the lithodesma dividing 

 the mass of the resilium mesially. 



SECTION A. EUSIPHONIA. 



Family 1. Pleuromyacidae. Zittel. 



Shell slightly inequivalve, hinge with an obscure projection or edentulous, the card/ mi! 

 border of one valve covering that of the other valve, which is supplemented by a sort of 

 laminar nymph, the ligament sub -internal between 

 them; area inconstant or obscure; pallial sinus 

 present; valves closed or slightly gaping. Trias to 

 Lower Cretaceous. 



Pleuromya, Ag. (Myacites, auct), (Figs. 686, 687). 

 Posterior side longer, somewhat gaping, hinge 

 margin with a thin horizontal lainin in rai-h vahv, 

 the left interior, the margin with a li-rble notch 

 behind the lamina; ligament pai-ivim-nlar. Ti-ia- 

 to Lower Cretaceous; abundant, but si Hum well 

 preserved. 



Gresslya, Ag. (Fig. 688). Like Pleuromya, but 

 the right hinge margin projecting over the left, 

 anterior side short, wide ; ligament parivincular, 

 almost internal, attached to an internal nyniph- 



like callosity in the right valve, which appears as a groove on internal casts. 

 in the Jura, especially in the Lias. 



<'li<>rostk<>\\. ' nt-ar MUM-IIW. .1, IntiTiial 

 cast, 1/1- 



Alanidant 



