Marshall. — Geology of the Central Kaipara. 



445 



Trichinopoly et Aryaloor Beds de l'lnde, les couches a Pachydiscus de 

 Patagonie (Hauthal), correspondant a la grande transgression senonienne 

 qui parait avoir atteint egalement Borneo et la Nouvelle Zelande." 



Kossmaticeras tenuicostatum n. sp. (Plate XXXIII, fig. 1.) 



The only specimen is large, measuring 142 mm. in diameter and 45 mm. 

 in thickness. Aperture oval. Shell extremely thin, ornamented with a 

 large number of very fine ribs which are not bent in the siphonal region 

 but they have a slight bend forward at the region about half-way between 

 the siphuncle and the umbilicus. There are no umbilical tubercles. The 



/' 



%M^i 





^ 



^£f r R< 



Fig. 2. — Suture-line of Kossmaticeras tenuicostatum. X H. 



suture-line is complicated. It is but little different from that of Ammonites 

 beudanti Brogniart from the Trichinopoly beds of India. (Pal. Ind., Cret. 

 Ceph., pi. lxxii.) The suture-line shows a distinct resemblance to that of 

 Kossmaticeras gemmatum Huppe, though there are considerable differences 

 in detail. The ornamentation is, however, completely different from that 

 of K. gemmatum. (Kilian and Beboul, loc. cit., p. 22 ; Steinmann, Neues 

 Jahrb. fur Min., &c, Bd. 10, 1895.) 



Lytoceras sp. (Plate XXXIII, fig. 3.) 



The only specimen of this genus is a fragment. The specimen measured 

 46 mm. in diameter and 18 mm. in 

 thickness. Cross-section nearly cir- 

 cular. The specimen has been 

 silicified, and that appears to have 

 destroyed the external ornamenta- 

 tion, though in one portion it is 

 still visible as a series of extremely 

 fine ribs. The specimen consists 

 of the body-chamber, but part 



of the next whorl remains, and 



. -, . ,. ' . .biG. 4. — Suture- line ot Lytoceras sp. 



on this a suture-lme is distinct 



which has the typical character of Lytoceras. The species appears to be 



closely related to Am. (Lytoceras) cola Forbes from the Ootatoor of India. 



(Pal. Ind., loc. cit., pi. lxxv, fig. 5.) 



X 7. 



