\M MOM , 



A'. /l.ii-Miif l,<*el 



\uiaitliei. .iin 9owb, Pi. 1":?. Bga, 561, 



!'. b'nilioiiia.m'iisr.N. riinlk. A. KOTHOMA;KNSIS. liion-. PI. I" 



/; /),,rmilly s/i,irji 



L7. Disci. chalk. A. METTBRHICHII, Hauer. PI. 108, flg. 564 



L. von Pinch has :it empted to distinguish ;i lame portion f 

 till' :il)ovr LiToups by <1 i Ifereliees ill the lobation \A/>/>. A/.-ml. 

 /trrlin. ls:j(i). :ind d'Orbiony lias further modified 'hem. 



i-t llic VMT'UMIS :it;nnpts wliich li:i\c IHTII iinidc t< 

 ci 1 on' of cli.-ios" in tlic :i)T:iiii:cin('ii! nf the AimiH'- 

 i:itr-. th:it of Prof. Alplicus Hy.-itt deserves i:irticiil;n- incut ion. 

 In liis .-irticlc on |-'ossil ( 'cplinlopoiN," pul)lisli-(l in tin- J>n/Irfin 

 Of the MH&-IHH of' ('uni/Hiro/i'iT 7<,<>l<>(/i/. i, 71, this Miitlioi" rcju'MnU 

 the Aimnonoids. including nil the ('('jjludopods with sriT.-itcd 

 or I'oliatiMl scptM.tlu- Clymenise, Goniatites, Ceratites, and Am- 

 inoniU's proj)cr "as :i distinct order from the Nnntiloids and 

 I>il>r;uichi:it'- ( 'ejihidopods :" the typic.-tl OTOUJ) <>!' this oi'dcr 

 U'inii' the so-c;dle(l M(.I IUS A innioiiites. This cnlni-^ed view of 

 the systematic position of the Aimnonoids is ly Prof. Hyatt 

 attrilmtcd to Prof. Au'a^i/. lut it is evident that Von IJiich had 

 :i glimmering of the same idea because his ^roups (mainly those 

 I have enumerated above) although permitted by him to remain 

 under tin- ijvneric name Ammonites were designated as families." 

 Prof. Kdward Sucs>. also, regarded the ^enns Ammonites as a 

 family, the typical o-nnips of which were of ^i-neric rank. 



1 -ive below the diau'iio-es of the families and ivnera in Prof. 

 Hyatt's paper ( which includes only liassic forms), pivmisinir that 

 whilst the discoN ci'ics of the embryonic dillen-liees between the 

 Xautiloids and A mnioiioids made by Prof. Hyatt are supposed by 

 some to indicate that tlie hitter should be included among the 

 dibranchiate rather than amoii^ the tet nibranchiatc cepiialopmls. 

 in any event, the elaborate subdivisions of 1 lie ^roiip are scarcely 

 \\arranted by the very lian^eabli- characters of the sj>e. 



rded as a con\-enience simply, the modified arrangement 

 of \'on IJueli. which we have uiven. appears |ireferable. 



I'rof. Hyatt reverses the use of " dorsal and abdominal " 

 in his descriptions of the shelN; inasmuch as the animal of 

 Nautilus and Ammonites i> placed with its abdominal side to the 



