ORDER III TELEODESMACEA 419 
Donaz, Linn. (Fig. 771). Anterior side longer, laterals weak. Upper Eocene and 
Recent ; about 100 species. Sub-genus Iphigenia, 
Schum. Recent. 
Egeria, Lea. Lower Eocene. 
Superfamily 14. SOLENACEA. Lamarck 
(emend.) 

Fic, 771. 
Dwellers in soft sea-bottom, narrow, elongated, _ Donux lucida, Eichw. Miocene (Sarmatian 
a , d Stage); Wiesen, near Vienna. 
modified for burrowing, gaping at both ends; foot ~~~ ) ; 
elongated, distally modified to serve as a piston or stilt within the burrow ; hinge without 
lateral laminae. 
Family 37. Solenidae. Leach. 
Shell substance as in Tellina, but the external layer showing cts cellular structure 
more clearly ; with a pronounced epidermis ; valves equal, free, usually truncate at both 
ends, and more or less inequilateral, with low beaks, smooth margins, not rostrate, smooth 
or feebly sculptured ; adductor scars narrow, elongate, dorsally distributed, pedal distinet ; 
pallial sinus small in species with anterior wmbones, and vice versa ; ligament and re- 
silium external, parivincular, seated on nymphs; area obscewre or none; hinge plate 
hardly developed ; hinge often with a thickened ray crossing the valves and serving as a 
buttress ; cardinals varying from one to four in each valve, usually a single slender 
radial laminar cardinal in the right, and two in the left valve, with or without one or 
two placed parallel with the hinge margin, simulating laterals; radial teeth usually 
more or less pedunculated, rarely bifid. Devonian to Recent. 
The Silurian forms heretofore referred to this family do not seem to belong to it, but 
Paluecosolen, Hall, is searcely distinguishable externally from some modern forms ; its hinge, 




























Fie. (72. Fic. 773. 
Solen subfragilis, Hichw. Miocene (Sarma- _ Cultellus Grignonensis, Desh. Caleaire 
tian Stage); Pullendorf, Hungary. Grossier ; Grignon, near Paris. 
however, is unknown. The species of this family are mostly much modified for a special 
mode of life, hence the variability in certain features, such as the siphons, foot, and ferma- 
ture of the mantle lobes. Novaculina has been 
naturalised in fresh water, and Tagelus appears to 
prefer estuaries. 
Solen, Linn. (Fig. 772). Seabbard - shaped, 
straight, with terminal beaks. Among the numer- 
ous sub-genera are: Hnsis, Schum.; Pharella, 
: Gray ; Ceratisolen, Forbes; Szliqua, Megerle; Cul- 
ae 2) b] to) > 
Fic. 774. * tellus, Schum. (Fig. 773). Tertiary and Recent. 
Solecurtus (Macha) Deshayesii, Desm. Cal- Palaeosolen, Hall. Devonian. Leptosolen, 
caire Grossier ; Grignon, near Paris. 1/}. : = 
Conrad. Cretaceous. 
Solecurtus, Blainv. (Psammosolen, Risso). Cretaceous to Recent. Sub-genera : 
Macha, Oken (Fig. 774); Tagelus, Gray ; Novaculina, Benson, fresh water. 
t=) /? Y b) Jv? ? ? 

