344 PKOCEEDINGS OF THE GEOLOGICAL SOCIETY. [April 24, 



rounded; surface marked by alternating groups of fine and coarse 

 concentric folds, or large undulations, 



Obs. This shell much resembles /. regularis, D'Orb., in shape, 

 size, and markings ; but the wing or hinge-area is not so long. It 

 is also almost identical in shape with /. LamarcJcii, I. latus, and 

 /. crisjyus, Mant. ; but the concentric undulations are not so unequal 

 and pronounced, neither had this shell a corrugated and thickened 

 fold along the hinge-line as in /. LamarcTcii ; the teeth or hinge-pits 

 are not seen. It is evident that this was an abundant species in 

 the Cretaceous seas of Queensland, its remains being numerous and 

 usually fragmentary. 



Loc. Marathon station. Form. Cretaceous. 



Inoceeamtjs allied to /. problematlcus, D'Orb. PL XXII. fig. 4. 

 Bef. Pal. Eranc. vol. iii. p. 510, pi. 406. 



I cannot see characters sufficiently good to distinguish specifically 

 this form of /nocei'amws ; andwe have only one specimen. D'Orbigny's 

 figures are variable enough to allow of any latitude in this species ; 

 and his figures 5 and 6 show characters occurring in our shell. /. 

 raytiloicles. Sow., may be referred to as having considerable resem- 

 blance ; a large number of specimens, however, should be examined 

 before the species can be determined, where so much variation and 

 similarity exists. 



Prof. M'Coy (loc. cit. p. 50) has described an Inoceramus as /. 

 Carsoni, and states that it exactly resembles /. mytiloicles, Sow., 

 but has a longer hinge-line, more pointed anterior end, and more 

 obtuse superior posterior angle than Sowerby's species. I had, prior 

 to seeing Prof. M'Coy's notice, referred this shell to I. mytiloides, 

 Sow. ; but it has more affinity with I. jproblematicus, D'Orb. 



Loc. Marathon station. Form. Cretaceous. 



Ceiocekas or Anctloceras. 



There is not enough of this specimen to warrant its being figured ; 

 and what may have been the character of the outer shell has to be 

 determined. It is evident the species was large ; but whether to be 

 referred to Ancijloceras or Crioceras is even doubtful. 



Mr. Moore, Quart. Journ. Geol. Soc. vol. xxvi. p. 257, t. 15. f. 3, 

 has described and figured a species of Crioceras from the Uj)per Ma- 

 ranoa district (E. Australia), which much resembles our specimen ; 

 his species, however, had an inner whorl, which determined the genus 

 to be Crioceras, through the non-involute condition of the coils. It is 

 difficult, if not impossible, to determine whether the Queensland fossil 

 is an Ammonites, Crioceras, or Ancyloceras. My reason for ventimng 

 to believe it to be Crioceras arises from the completeness of the 

 ventral surface of the whorl and what would appear to have been 

 a space between the first and second coil or whorl, now filled by the 

 matrix in which the shell is imbedded. Our shell must have been 

 of considerable size, measuring little less than 12 or 14 inches in 

 diameter, and the ribs faintly bifurcate from the centre of the whorl, 

 but without any tubercle at the point of bifurcation. 



