218 CARBONIFEROUS CEPHALOPODA OF IRELAND. 



suture-line — peripheral lobe ^ deep and undivided, peripheral saddles " rounded ; 

 lateral lobes narrow and deep, lateral saddles broadly rounded. 

 Upper Devonian and Carboniferous. 



80. Brancoeeras oruatissimum. 81. Braucoceras Enuiskillenense.* 



Genus Pericyclus (Mojsisoi'lcs, 1882, emend. Hi/off, 1883). — Shell involute, sub- 

 gloliose to compressed, narrowly to Avidely umbilieated ; surface of test with strong, 

 direct, transverse ribs, forming a shallow sinus on the periphery, but usually without 

 any sinuosity on the sides of the shell ; constrictions present in some species ; suture- 

 line — peripheral lobe divided by a small median saddle ; ' peripheral saddles broadly 

 rounded or spatulate ; lateral lobes pointed, deep ; lateral saddles broadly rounded, 

 or forming a shallow arch ; usually with a small auxiliary lobe at the umbilicus. 



Carboniferous. 



82. Pericyclus funatus. 88. Pericyclus trapezoidalis. 



83. ,. fasciculatus. 89. „ Bailyi. 



84. ., Doohylensis. 90. „ rotuliformis. 



85. ,, multicostatus.* 91. ,, plicatilis. 



86. „ Foordi. 92. „ Clanensis. 



87. „ subplieatilis. 93. „ Leesoni. 



GevKS GLTrniocEiiAS {Eyaft, 1883, emend. J. Perrin Smith, 1897). — Shell 

 involute, globose to compressed ; umbilicus usiiall}' narrow or closed ; periphery 

 strongly convex to subacute ; surface of test smooth or finely striated, often with 

 periodic constrictions; suture-line — peripheral lobe divided by a small median 

 saddle ; peripheral saddles narrow, romided or pointed ; lateral lobes acute or sub- 

 acute, deep ; lateral saddles broadly rounded or obtuselj^ angular ; usually with a 

 small auxiliary lobe at the margin of the uml)ilicus. 



Carboniferous and Permo-Carboniferous. 



Sub-genus Sphenocekas,* sub-gen. nov. ( = Ghjpliioceras, Section I [pars], of 

 Hyatt). — Shell involute, globose, with narrow or closed lunbilicus, the whorl semi- 

 lunate in section ; surface of test longitudinally or spirally striated, with periodic 

 constrictions ; suture-line — peripheral lobe with a prominent median saddle di^-iding 

 it into two acute terminations ; ])eripheral saddles inclined towards the umbilicus, 

 often acute ; lateral lobes acute or very nai'rowly rounded ; lateral saddles ])roa(lly 

 rounded, sometimes with a subacute apex. 



94. Splieuoceras spbfericuiu. 95. Sphenoceras crcuistria. 96. Sphenoceras striatum. 



' Known also by the names " outer," " external," and " ventral " lobe. 



"- Known also as the " lateral " saddle or " first lateral " saddle. 



^ Called also the " siphonal " saddle. 



* Referring to the wcdi,'c-shapcd peripheral saddles ami lateral lolics. 



