14 PKOCEEDIlSrGS OF THE NATIONAL, MUSEUM vou 78 



more rounded; lobes with more and deeper marginals; principal 

 saddles sometimes bifid. 



Hypengonoceras Spath,^^ genotype H. warthi (Kossmatt).^° AI- 

 bian. Shell with low folds, elongate marginal nodes, alternating 

 in position along the margins of the flattened venter. Ribs termi- 

 nating at both ends in small tubercles (according to Stoliczka, but 

 none shows in his figures). Suture relatively complex, with all 

 saddles rounded, bifid and with smaller marginals suggested; lobes 

 with numerous small, pointed marginals. 



Parengonoceras Spath,^^ genotype P. ehrayi (De Loriol).^- Al- 

 bian. Shell with apparently smooth flanks in early stages and with 

 venter truncated and bordered by elongated marginal tubercles; in 

 later stages shows ribs and three rows of lateral nodes. Suture rela- 

 tively complex, with saddles rounded, bifid, and dissected by many 

 small marginals; lobes with many small blunt marginals. 



Metengonoceras Hyatt, genotype M. inscriptum Hyatt.^^ Albian. 

 Shell with broad folds in some species; very rarely faint nodes also;' 

 usually smooth. Venter in early stages comparatively broad and 

 concave; later narrow but distinctly truncate; still later becomes 

 first acute and then rounded (according to Hyatt, but see below). 

 Suture much like that of some species of Engonoceras but rarely has 

 divided saddles. 



Epengonoceras Spath,^* genotype E. duinbli (Cragin)." Ceno- 

 manian-Turonian. Shell with nearly smooth flanks, only low broad 

 flolds showing on some shells; venter relatively broad, slightly con- 

 cave in early stages, becoming narrow (1 to 2 millimeters) but still 

 concave or flat in later stages, and in old age rounded. The shell 

 is not acute at any stage of growth, though the internal molds often 

 are narrowly rounded (see below) in the adult stages and show no 

 reflection of the truncation of the shell. Suture, in general, has the 

 lobes more deeply dissected than in Metengonoceras^ but the saddles 

 are usually simple as in that genus. 



* Spath, li. F., On Cretaceous Ammonoidea from Angola : Roy. S<3c. Edinburgh Trans., 

 vol. 53, pt. 1, p. 112, 1922. 



^'' Kossmatt, Franz, Untersuchungen liber die sUdindische Kreideforraation : Beitr. Palii- 

 ontologie Oesterr.-UDgarns u. des Orients, vol. 9, p. 176, pi. 20, flg. 8, 1895. Stoliczka, 

 Ferdinand, The fossil Cephalopoda of the Cretaceous rocks of southern India, Amn?'oniti- 

 dae : Falaeontologia Indica, vol. 1, p. 92, pi. 4S, flg. 2, 1805. 



^ Spath, L. F., On a new ammonite (Engonoceras iris, sp. n.) from the Gault of Folk- 

 stone : Ann. Mag. Nat. Hist., ser. 9, vol. 14, p. 508, 1924. 



^ De Loriol, P., fitudos sur la faune des couches du Gault de Cosne : Soc. paleont. Suisse 

 M6m., vol. 9, p. 7. pi. 1, fig. 1, 1882. 



"' Hyatt, Alpheus, Pseudoceratites of the Cretaceous : U. S. Geol. Survey Mon. 44, pp. 

 179-182, pi. 25, figs. 5-9 ; pi. 26, figs. 1-4, 1803. 



** Spath, I.. F., On a new ammonl^te (Encjoiwcerus iris, sp. n.) from the Gault of Folk- 

 stone : .Vnn. Mag. Nat. Hist., ser. 9, vol. 14, p. 508, 1924. 



^ Hyatt, Alpheus, Pseudoceratites of the Cretaceous : U. S. Geol. Survey Mon. 44, p. 185, 

 pi. 27, figs. .3-14, 1903. 



