220 CARBONIFEROUS CEPHALOPODA OF IRELAND. 



Family — Pbolecanitid.e, Hyatt, 1883 (emend. Karpinsky, 1890; Hyatt, 1900). 



[Sub-order Phyllocampyli, Hyatt, 1900 (pars), in Eastman's transl. of von Zittel's ' G-rundz. d. 

 Palseont.'] 



Discoidal or involute, compressed, subquadrate, or helmet-shaped in section. 

 Primitive forms with undivided peripheral lobe ; more specialised forms with hastate 

 lobes and saddles and divided peripheral lobe. 



Genus Prolecanites (Mojsisovics, 1882; emend. Hyatt, 1883, 1900). — Shell 

 discoidal, compressed, evolute, widely umbilicated, with a narrow, sometimes 

 flattened periphery. Surface of test smooth or striated. Suture-line — saddles 

 entire, narrowly rounded, constricted near the base, giving them a hastate appear- 

 ance ; lobes obtusely pointed ; peripheral lobe undivided ; two or three lateral 

 lobes ; auxiliary lobes absent or few in number ; inner (antiperipheral) lobe narrow, 

 deep, pointed, with a flat, broad, rounded lobe on each side of it. 



Devonian and Carboniferous. 



120. Prolecanites compressus. 



CONCLUDING REMARKS. 



I. Paleontology. 



In C. R. Eastman's translation of von Zittel's ' Grundziige der Palceontologie ' 

 (1900) a new scheme of classification of the Cephalopoda is introduced, the work of 

 the late Professor Hyatt, which, though partly embodying the older scheme of 

 the well-known 'Genera of Fossil Cephalopods' (1883), contains important 

 modifications, involving the erection of many new sub-orders, groups, families, and 

 genera. The scheme is complicated and somewhat defective as it stands ; type 

 species of the new genera are often omitted, while in other cases though the 

 type species is named there is no description of the genus. An enumeration of 

 typical forms would have greatly lessened this defect. We are told, however, in a 

 note by the translator that " the classification and diagnoses are condensed from an 

 exhaustive monograph on fossil Cephalopods, at present still in MS., which 

 embodies the results of his [Hyatt's] life-study." The deficiencies referred to may 



