136 



SUPPLEMENT TO THE 



Families or Groups 





Attachments 





Position of loop 



of spiral-bearing 



Direction of spirals. 



to 



Shape of loop. 



in relation 



Bracbiopoda. 





hinge-plate. 





to the spirals. 



5. Anazygida, 



Anazyga as in Zygospira 



Anazyga and 



Simple V-shaped loop 



At the base of the spirals, 



Dav., 1882 



(AtrypidcB) 



Dayia as in 



with rounded or angu- 



and directed upwards, 



Anazyga 



Bayia and Hindella as 



Atrypa 



lar extremity, and 



being either exterior to 



Dayia 



in Nucleospira 



Hindella as in 



sometimes having a 



the spirals, as in Ana- 



Hindella 





Nucleospira 



short spine-like con- 

 tinuation 



zyga, or between and 

 interior to the spirals, 

 as in Hindella, or be- 

 tween the primary 

 lamellae on the dorsal 

 side of the spirals, as in 

 Dayia. 



At p. 82 of this Supplement Uncites has been placed in the Family Nucleospirid^e, 

 but subsequently Mr. Glass thought it should be put under SpiRiFERiDiE, because it has 

 straight attachments to the hinge-plate and its spiral arrangement is very like that of 

 Spiriferina. The loop seems almost horizontal and does not go backwards so far 

 towards the ventral side of the spirals as in Nucleospira. As far as we can see all those 

 specimens whose spirals have straight attachments to the hinge-plate should be included 

 in the Spiriferid^. This characteristic is very marked, and there is nothing in the 

 case of Uncites to override its significance. 



As to the Anazygid^e, it seems to us that the rising of the loop from the bottom 

 of the spirals is a very permanent and unmistakable character, and well marks off the 

 class. 



Of course all classes or families have mutual likenesses, and more or less run into 

 each other, and we have to choose for purposes of classification, so far as is possible, the 

 most marked divergencies. Now 



Spiriferida; is clearly marked by straight attachments to the hinge-plate. 



Anazygidce, by loops rising from bottom of spirals. 



Atrypida, by loop exterior to and above spirals. 



Nucleospirida, by loop in centre being simple and extending horizontally from dorsal 

 to ventral side of spirals. 



AtJiyridai by loop more complex and extending upwards from the centre of the 



Everything, however, in connection with the classification of the Brachiopoda must 

 be considered as provisional. A final arrangement is not yet attainable. 



