TRENTON CONGLOMERATE OF RYSEDORPH HILL 51 



Freeh (tab. p. 77) gives as its habitat the Knollenkalk a,? and ad 

 which are synchronous with the Glenkiln shales (Normans kill 

 shales) and the corresponding lower middle graptolite shales 

 of Scania and of Norway. Another European form with cari- 

 nate glabella is Lonchodomas carinatue, which how- 

 ever has a more elongate cranidium, and is found in another 

 horizon (Chasmops-Kalk of Westrogothia) according to Remel^. 

 The subdivisions of Ampyx, proposed by Forbes and Angelin, 

 have been fully discussed by Nicholson and Etheridge,^ and 

 lately by Vogdes.^ To restate shortly a case repeatedly eluci- 

 dated, the genus Ampyx proposed by Dalman was divided in 

 1849 by E. Forbes^ into: 



1 Ampyx (Dalman) proper, vdth the head long and five seg- 

 ments of the thorax. 



2 Brachampyx Forbes, 1819, with the head short and round 

 and six segments to the thorax. 



-Dr Angelin in 1854^ proposed the subdivision of his family into 

 three genera: 



1 Lonchodomas Angelin, with a lanceolate glabella, ter- 

 minating in an elongate prismatic spine. Type L. (Ampyx) 

 roetratus Sars. 



2 Ampyx Dalman, with an oval glabella, terminating in a 

 round spine, and six thoracic segments. Type Ampyx cos- 

 tat u s Broeck. 



3 Raphiophorusi Angelin, with an obiovate glabella^ having 

 au abrupt apical^ spine, and five thoracic segments. Type K. 

 setirostris Angelin. 



It appears by a comparison of these subdivisions, that Angelin 

 retained the term Ampyx for forms with six segments, and 

 thus applied it in the sense of the originator of the term, Dal- 

 man, who described Ampyx as having six isegments; while 

 Forbes proposed his term, Brachampyx, for just such six 

 segmented forms. Nicholson and Etheridge, therefore, seem 



1 Monograph Sil. foPS. Glrvan district In Ayrshire. 1880* p. 178. fT« 



2 Am. geol. 1693. 11:99. 



' Geol. sur, Gt. Br. Mem. Dee. 2, 1849. pt 10, p. 3« 

 « Pah Scandin. p. SO. 



