HAUGIA. 143 



The first are distinguished by their ornamentation from all genera hitherto 

 mentioned, except Lillia ; but from that the high hollow-carina and the acute, 

 unfurrowed, ventral area at once distinguish them. 



The second exhibit, in outward aspect, convergence to Pseudolioceras, thus 

 exemplifying my statement that the gradual progress of the forms of the 

 various genetic series is towards a similar shape (p. 133). They may be 

 distinguished from Pseudolioceras by a much larger hollow-carina, a ventral area 

 more completely rounded where the test is absent, and by a very different suture- 

 line (compare Plate A, figs. 37 and 22). The superior and inferior lateral lobes 

 are more developed, and take up more lateral space than in Pseudolioceras ; while 

 the auxiliary lobes are fewer in number but larger, and yet are cramped into a 

 smaller space. The ribs also are less truly sigmoidal. The agreement of this 

 branch in the matter of lobes, and practically in every character except knobs, 

 with the type of the genus, shows that there is a close relationship between them. 



Am. variabilis was placed by Hyatt 1 in his genus Hammatoceras, merely, I 

 presume, on account of its resemblance in ornamentation — especially the knobs on 

 the inner margin — to Hammatoceras insigne. Wright, and other authors, who did 

 not recognise Hammatoceras, kept the species inWaagen's later genus Harpoceras. 

 Haug 2 placed it to Hammatoceras with a query, but included it, not in the Insigne- 

 group, but in the Sowerbyi-groxvp ; while he placed Am. Ogerieni, Am. navis, and 

 Am. malagma in a group with Am. propinquans and others (Sonninia, Bayle). 

 The entirely different character of the lobes separates Haugia from Hammatoceras ; 

 while a study of the other members of the genus shows that the knobs on the 

 inner margin were an inconstant character, and, in the case of Haugia variabilis, 

 merely an example of deceptive outward similarity. The same remarks apply 

 concerning Haugia and Sonninia ; the latter possesses a far more florid, very 

 much branched suture-line. 



Dumortier 3 placed Am. navis and Am. malagma in his section " Podagrosi " 

 (Lillia, pars, see p. 109) ; but the large hollow-carina and the unfurrowed ventral 

 area show that they do not belong there. Haug 4 placed Am. Eseri in " the group 

 of Am. hjthensis " (Pseudolioceras, p. 81) ; but I have just previously pointed out 

 the differences between Haugia Eseri and Pseudolioceras. Quenstedt, 5 by giving 

 the same form the name Am. radians compressus, regarded it as a variety of Am. 

 (that is, Grammoceras) radians; but though it certainly shows a very great 



1 ' Ceph. Mus. Comp. Zool. Bulletin,' p. 89. His description applies to Hammatoceras insigne, 

 but not to Am. variabilis. 



2 " Beitrage Monog. Harpoceras," ' Neues Jahrbuch fur Mineralogie, &c.,' Beil.-Bd. iii, p. 656. 



3 ' Etudes pal. Bassin Khone,' pt. iv, p. 82. 

 * Op. cit., p. 628. 



6 ' Cephalopoden,' p. 112. 



