UPPER PALAEOZOIC FAUNAS 169 



while Capulus and the Serpula-liko, Vermicularia fore- 

 shadowed the teeming Taenioglossa of later periods. 

 The Euthyneura perhaps showed most evolutional 

 activity among Gastropods. Tectibranchiata, such as 

 Actaeonina, appeared first in the Carboniferous; 

 Conulariid Pteropods almost disappeared at the same 

 stage ; and the earliest known Pulmonate, Hercynella, 

 occurred in the Devonian. The oldest recorded land- 

 snail, Dendropupa> has been found in the Coal Measures. 



Cephalopoda are striking, and often abundant, fossils 

 in the Upper Palaeozoic. Nautiloids were joined by 

 Ammonoids in the Devonian ; the record of the former 

 is one of slow decline, that of the latter of extra- 

 ordinarily rapid specialization. Orthoceras maintained its 

 primitive form, with morphogenetic monotony, through- 

 out the era, and endured even to the Trias. Cyrtoceras 

 (PI. xii. fig. 5) is a characteristic Devonian Nautiloid ; 

 while more completely discoidal shells, such as those 

 of Stroboceras and Coelonautilus> are relatively abundant 

 in the Carboniferous. But few groups of Nautiloids 

 survived the Palaeozoic ; all such enduring types (except 

 Orthoceras) were more or less strongly involute. 



The Upper Palaeozoic has been described as the 

 '" age of Goniatites." Although later discoveries among 

 Permian Ammonoids have shown this generalization to be 

 inaccurate, the stage of evolution indicated by the com- 

 prehensive word " Goniatite " was certainly prevalent in 

 Devonian and Carboniferous times. Bactrites, a straight 

 shell distinguished from Orthoceras (or its ally Proto- 

 bactrites) merely by the ventrad situation of the siphuncle, 

 may be the true radical of the Ammonoid stock. It is 

 found in the Devonian in company with a large series 

 of more advanced forms. Of these, the Clymeniidae 

 are especially interesting. Clymenia } unlike all other 

 Ammonoids, has the siphuncle on the dorsal side of 



