664 



MOLLUSCOIDEA. 



from the Devonian to the Lias, but the Silurian genus Coelospira 

 may possibly belong here. 



In the genus Koninckina^ comprising only the K. Leonhardi (fig. 520) 

 of the Upper Trias, the shell is circular, concavo-convex in form, very 

 thick, with a smooth surface and an impunctate shell-structure. The 

 hinge-line is straight, with teeth and sockets, but without an area or 

 deltidium. The ventral valve is very convex, and a large part of the 

 cavity of the shell is occupied by the spirally-coiled brachial processes. 

 Nearly allied to Ko?iinckina is the Devonian genus Anoplotheca, in 

 which the spirals for the arms are more largely developed than in the 

 former. 



Lastly, the genus Koninckella has been founded by Munier-Chalmas 

 for the reception of some of the small Brachiopods of the Lias which 



Fig. 520. — Koninckina Leonhardi, from the 

 Trias of St Cassian. The left-hand figures 

 show the ventral and dorsal aspects of the 

 shell, of the natural size. The right-hand 

 figure is enlarged, and shows the spiral brachial 

 processes. (After Zittel.) 



Fig. 521. — Kon- 

 inckella Hasina. 

 Lias. The small 

 cross below the 

 figure indicates the 

 real size of the shell. 



were formerly referred to Leptcsna. In this genus the shell (fig. 521) is 

 concavo-convex, smooth, and in general aspect not unlike a Leptczna, but 

 the arms are supported by spiral brachial processes of two or three coils, 

 which carry lateral calcareous spines for the support of the cirri of the 

 arms. The type of this genus is the Koninckella liasi7ia of the Lias. 



Family 4. Spiriferid.e. — In this family the shell is biconvex, 

 its minute structure being sometimes punctated, sometimes fibrous. 

 The arms were entirely supported upon two spirally-rolled calcareous 

 lamellae, which spring from the hinge of the dorsal valve — the bases 

 of the spires being turned towards each other, while their apices 

 are directed laterally towards the cardinal angles of the shell (fig. 



493)- 



The family of the Spiriferidce is pre-eminently Palaeozoic, but 

 several forms extend into the older Secondary rocks. No member 

 of the family, however, has yet been found in rocks younger than 

 the Lias. Of the genera of the family, the most important is the 

 genus Spirifera, or Spirifer (figs. 522, 523, 524, and 526), in which 

 the valves are articulated by teeth and sockets, and the shell is not 

 punctated. The hinge-line is long and straight, and the well-marked 

 hinge-area is divided across in each valve by a triangular fissure, 



