78 SUPPLEMENT TO THE 



ON SPIRAL-BEARING BRACHIOPODA. 



Among the Brachiopoda, one of the most interesting of the groups is that of the spiral- 

 bearing genera and species, or those genera and species that are provided with calcified 

 spirally-coiled lamellae for the support of the fleshy, brachial, or labial appendages. 



Although fleshy labial appendages more or less coiled exist in recent species, such as 

 Rhynchonella, Lwgnla, &c., in no recent case have they been found supported by calcified 

 spirally-coiled lamellae ; nor have any, as far as we are aware, been so provided since the 

 commencement of the Oolitic period. Spiral-bearing Brachiopoda are essentially charac- 

 teristic of the Palaeozoic period, though they have continued to appear in diminished 

 numbers up to the close of the Liassic epoch. 



It is not yet possible to group the genera definitely into families, for it is only within the 

 last few years that their real characters have been approached and understood ; and much 

 further investigation in the right direction, among the various unexamined species, will 

 require to be undertaken before we may venture to generalise definitely upon the subject. 



It has been long known that certain species were provided with lamellae spirally 

 coiled, and as far back as 1815 the genus Spirifera was proposed by Sowerby, although 

 at that period misunderstood by him ; but the most important study of their different 

 modes of convolution, loops, and attachments to the hinge-plate, is an almost new kind 

 of investigation, requiring much skill, acumen, and patience, as these attachments have in 

 most cases to be sought for in specimens filled with a hard, and often intractable 

 matrix, and many examples have in some cases to be sacrificed before a satisfactory 

 result is attained. The best mode of operating will be referred to in the sequel. 



Prominent in this difficult study has been the Rev. Norman Glass, to whose inde- 

 fatigable perseverance and consummate skill I am indebted for the possibihty of laying 

 before my readers a large amount of positive and most valuable information. I can find 

 no words sufficiently expressive to convey the gratitude I feel towards him for the 

 unrelaxing energy he has displayed during upwards of three years in this difficult kind 

 of investigation. I have also received much help from Mr. R. P. Whitfield, of the 

 American Museum of Natural History in New York, as well as from Herr Zugmayer, of 

 Vienna, both of whom communicated to Mr. Glass and to myself the specimens they had 

 been able to develop. These are described and figured in Professor Hall's monumental 

 work on the ' Palaeontology of New York,' and by Herr Zugmayer in his work on the 

 ' Brachiopoda from the Rhaetic Rocks of Austria.' 



Many genera and several families have been proposed from time to time by difiierent 



