84 



SUPPLEMENT TO THE 



First Division 



Second Division 



i IT, 



/-Atrypa, Dolman, 1828; type A. re^f/cw/^m = Spirigerina, A. 

 \ cVOrhigny, 1847. 



^Coelospira, Hall, 1863 ; type C. concava, Hall. 

 ^Thecospira, Zuf/mayer, 1880; type Thecidium Haidinijen, Suess. 

 Anoplotheca, F. Sandherger, 1855; type A. venusia, Schnur. 

 Koninckina, Suess, 1853 ; type K. Leonardi, Wiesman. In 

 1855 I proposed a family, Koninckinida, for this and similar 

 species. 

 Koninckella, Munier-Chahnas, 1880 ; type Leptcena Liasiana, 

 Bouchard. In 1880 M. Munier-Chalmas proposed a family 

 KonincTcidce, for Konmckina and Koninclcella ; but I had 

 proposed such a family previously. 

 ^Davidsonia, Bouchard, 1 849 ; type D. Verneuilii, Bouchard. 

 Th' H "D" ■ ■ I Glassia, Dav., 1881 ; type G. obovafa, Sow. 



I Zygospira, Hall, 1862; type Z. modesta, Hall. 

 Atkypa will be found minutely described in the sequel. In this excellent genus the 

 conical spiral appendages, first attached to the hinge-plate, are placed side by side, with 

 their extremities facing the bottom of the dorsal valve. The principal stems of the spiral 

 coils at a short distance from their attachment to the hinge-plate are connected by a narrow 

 band. 



Ccelospira, Hall, is so nearly connected with Atrypa 

 generically that it must remain a question whether it can be 

 separated. 



The second division contains several genera more or less 

 closely related, with a very slightly convex, flat, or concave 

 dorsal valve, and with very little space between the 

 valves for the animal to occupy. The spiral coils have 

 consequently in most cases a very moderate elevation; 

 some are coiled on the same plane, or vertically, the extremities being directed 

 towards the bottom of the ventral valve. This is especially observable in Zugmayer's 

 figures of Thecospira, which externally bears so much resemblance to certain 

 species of Thecidium that it was placed in that genus by Professor Suess, who 

 was not then acquainted with its spirally coiled lamellse. It also, as well as Davidsonia, 

 attaches itself by a portion of its ventral valve to marine objects. The attachments of 

 the spiral coils in Thecospira are very similar to those of Atrypa. I have never seen the 



Ccelospira concava. After Hall. 



spirals of Ko 

 Chalmas. 



ickella, and their existence is given on the authority of Mr. Munier- 



Koninckinn, and probnbly Davidsonia ; and he would, no doubt, have included Thecospira and Koninclcella 

 had they then been discovered and published. 



