﻿Vol. 66.'} SPECIES OF AMMONITES AND BRACHIOPODA. 



97 



Note. — In the side view the umbilicus is imperfect, and so 

 appears too large : the dots show the true position of the inner 

 margin of the last part of the whorl, giving an inclusion of about 

 half a whorl. 



Distincti on. — It is separable from any other species of the 

 genus, by the deficiency and paucity of its costation, as well as by 

 other characters. 



Locality and stratu m. — Bradford Abbas (Dorset), from the 

 Fossil Bed ; three specimens, whereof the one figured is the largest. 

 It is evidently from the discites zone, and there is reason to think 

 that it occurs in the Yellow Conglomerate Bed of Burton Bradstock. 



Fig. 



2.- 



-STceleton outline of the lobes of 

 Burton ia. 





Family Hammatoceratidae. 



Genus Burtonia, nov. 



Whorls stout, inclusion considerable ; ornament when present 

 coarse ; carina small, solid ; suture-line not ornate ; superior lateral 



lobe somewhat long, 

 Fig. 1. — Skeleton outline of ilte broad-stemmed, tri- 



lobes o/Shirbuirnia. fici ; inner lobes 



much retracted (de- 

 pendent) — running 

 back and pointing 

 across the whorl. 



Distinction. — 

 From its ally, Ham- 

 matoceras, the coarse 

 ornament and the 

 much less complex 

 suture-line ; from 

 any of the Hildo- 

 ceratidse, to some 

 genera of which it 

 has superficial re- 

 semblance — to Kili- 

 ania for instance, 

 — the retracted or 

 dependent inner 

 portion of the 

 suture-line. 



This genus be- 

 longs to a series 

 entirely different 

 from Shirbuirnia. 

 The essential cha- 

 racter is the retract- 

 ed or dependent inner portion of the suture-line. Instead of the 

 lobes appearing like so many protrusions from a straight line, as in 

 fact the lobes of Shirbuirnia do, the inner portion of the suture-line 

 Q. J. G. S. No. 261. h 



