210 TIMSOA. (JONIOCKRAS, ETC. 



Tretoceras, Salter. 



Founded OH (J. bisiphonatum, Sowb.. from the Caradoe sand- 

 stone (Silurian). IJrit.. in which the septa arc apparently perfo- 

 rated by two siphuncles : one of which is a deep lateral cavity 

 continuous with the terminal chamber the cavity affecting at 

 least seven of the uppermost septa, if not the whole. 

 T. HISIIMION ATUM. Sowb. PI. 97. HO-. 481 . Silurian. Ilv//f>-. 



Thisoa, Montf. 



Shell ovate-elono-ate. cucumber-shaped ; nppnivntly t wo siphons 

 running parallel the whole leug'tli of the she'll, one of which trav- 

 erses M sort of narrow lateral cavity; there are also a number 

 of false siphons or holes, which do not extend the entire length 

 of the shell. 

 T. sii-iioN ;.\us. Sei-res. I'l. 104. figs. 571. ;">7^. .Jurassic. Fratit-t*. 



Gonioceras, Hsill. 



Shell Hatteiied. with extremely salient angles; septa sinuous; 

 section of shell, an extended ellipse with project in' angles; 

 siphuncle vent ral. 

 (. ANCKi'S. Hall. IM. 97. liii's. 4s:;. 484. L. Silurian. 



Colpooeras, Hall. 



This is [)rohably only :i siphon of one of the larger species of 

 Ort hocerata. 

 ( 1 . \ iu<iATi:\i. Hall. I'l. ( .7. li.ii 1 . 4Sn. L. Silurian. tfew YurL-. 



Dictyoceras, Hichw. 

 Is probably an Orthoceras covered l\ a ltr\'o/oan or coral. 



Genus CLINOCERAS, 



Shell conical (allied to Ln:i-n<'i>rn#. McCoy), the siphuncle side 

 st raiji'lit. the others more or less curved; a constriction below 

 the body-chamber. Septal border with an obtuse-angled saddle 



on the. siphuncle side, with gently rounded lobes and two slightty 



marked lateral saddles. 



('. iK.\s. Maseke. 1*1. I0f). li'. f)S7. Krratic L.Silurian lilocks. 

 Prussia, 



