462 Dr. C. Semper on the Identity in Type 



Plate XXIV. 



Fig. 1. Aspidopht/Uum Htulei/anum, Thorns., transverse section, enlarged ; 

 1 A, transverse section of the same, natural size. Lower Car- 

 boniferous, Thirdpart, Beith, Ayrshire. 



Fiff, 2. Aspidophyllum, sp., transverse section. Lower Carboniferous, 

 Gateside, Beith, Ayrshire. 



Fig. 3. Dibunophyllum Muirheadi, Nich. & Thorns., transverse section ; 



3 A, longitudinal section of the same. Lower Carboniferous, 

 Gateside, Beith, Ayrshire. 



Fig. 4. Dibunophyllum, sp., view of the interior of the calice, showing 

 the arrangement of the ridges formed by the free edges of the 

 vertical lamellae of the central area ; 4 a, transverse section of 

 the same. Lower Carboniferous, Langside, Beith, Ayrshire. 



Plate XXV. 



Fig. 1. Dibunophyllmn, sp., transverse section, showing the mesial lamina 

 which divides the central area ; the septa become vesicular and 

 broken up towards the circumference by the great development 

 of the dissepiments. Lower Carboniferous, Langside, Beith, 

 Ayrshire. 



Fig. 2. Transverse section of a young form of Dibunophyllmn ; 2 a, external 

 aspect of the same, showing the interior of the calice. 



Fig, 3. Dibunophyllum M' Cliesneyi, Nich. & Thoms., showing the interior 

 of the calice ; 3 a, transverse section of the same ; 3 b, longitu- 

 dinal section of the same, showing the unusual fact that there 

 is but a single columellarian line, as in Clisiophyllum. Lower 

 Carboniferous, Brockley, Lesmahagow. 



Fig. 4. Dibunophyllum Muirheadi, Nich. & Thoms., transverse section ; 



4 a, longitudinal section of the same, showing the normal struc- 

 ture of the genus. Lower Carboniferous, Gateside, Beith, Ayr- 

 shire. 



Fig. 5, Dibunophyllum Muirheadi, Nich. & Thoms. (?), transverse section. 



Lower Carboniferous. 

 Fig. 6. Dibunophyllum, s^., interior view of the calice; 6 a, transverse 



section of the same. Lower Carboniferous. 

 Fig. 7. Dibunophyllum, sp., transverse section. Lower Carboniferous. 



[To be continued.] 



LIV. — On the Identity in Type of the Annelids and Vertebrates. 

 A preliminary Communication *. By C. Semper. 



The old view of Geoffroy St.-Hilaire and Ampere concerning 

 the agreement in affinities of tlie Articulates and Vertebrates 

 was, as is well known, completely supplanted by the type theory 

 of Cuvier and Von Baer, which supposed a great difference in 

 the structure of the two groups. And not without good reason ; 

 for if the inversion of an Articulate so that its ventrum was 



* Translated from the ' Physikalisch-medicinische Verhandlungen zu 

 Wiirzburg,' by P. Herbert Carpenter, B.A. 



