4 



MS 



Fig- 3 of GossELET transitional between lonsdalci and vcriicuili. 



4 



5 

 29 



41 



50 



I. 

 I. 



and 11. 

 and 2. 



It is seen from the above table (i) that the majority of the specimens of 

 GossELET belong to the variety lonsdalci Murchison ; (2) that there is no 

 group or variety of Peixizzari which includes the group cyliiidrici, the most 

 extremely transverse form ; and (3) that Pellizzari's varieties vicari and 

 gorta?ii contain no other forms than those grouped by Gosselet in obovatiy 

 the lyrate type. Again, the variety lonsdalci represents all such moderately 

 transverse forms- as attoiiiati, clongati and hcinicycli, but none of either 

 cyliiidrici, proquadrati or oboi-ati. The variety archiaci seems to have no 

 equivalent form among the specimens which were studied by Gosselet, 



In a word, there seems to exist no correspondence between the classifi- 

 cations of the two naturalists when spoken of in an exact sense. Yet Gos- 

 selet's division suggests the possibility of separating the species into several 

 subordinate groups which are closely related to one another in a series. 

 Here, G^ sselet may be quoted in order to suggest the mutual relations of 

 these varietal forms. " Lorsque le Spirifere est jeune, il est de forme obovale ; 

 ce sont les ailes qui croissent ensuite le plus rapidement, augmentent la largeur 

 de la coquille ; plus tard, la croissance se produit principalement en longeur, 

 le front s'elargit, les ailes s'arrondissent. Tel individu, qui appartinait ay 

 groupe des clong'ati, passe dans celui des hcinicycli, puis dans celui des 

 obovati. II arrive meme que les eperons se trouvent englobcs dans la 

 coquille." (P. 9.) 



Gosselet has given a very detailed diagnosis of the species, but the 

 species itself is so inconstant a form that his description is not so valuable as 

 ■it first appears. The species no doubt possesses the essential characteristics- 

 of the Genus Spirifer. lis most significant feature, however, is the extra- 

 ordinary regularity of the surface ornamentation. " Les cotes du bourrelet et 



