202 University of Texas Bulletin 



siders this species as a Pulchellia and it certainly has the greatest sim- 

 ilarity with this genus if we do not take into account Metoecoceras. . Com- 

 paring the figures of Petrascheck with those of the American Metoeco- 

 ceras we note a surprising similarity ; for example, between figure 4 of Pe- 

 trascheck and figure 2 of Stanton, 1 and between, figure 3 of Petrascheck 

 and figure 10 of plate 15 of Hyatt. 2 



The suture of the specimens from Saxony is imperfectly known, but the 

 elements which can be recognized in figure 4 of plate 7 and figure 5 of the 

 text (p. 141) of Petrascheck, coincide very well with those of Metoecoceras. 



Petrascheck identifies his specimens with Ammonites Geslianus d'Or- 

 bigny,* but Sayn points out that the figure of d'Orbigny differs very much 

 from the figures of Petrascheck. It is possible that Ammonites Geslianus 

 d'Orbigny belongs also to Metoecoceras but this can not be decided as long 

 as the suture is entirely unknown. The specimen figured by Gueranger" 

 under the name of A. Geslianus is so badly preserved that no details can be 

 recognized. What Geinitz 5 figures as A. Geslianus d'Orbigny seems to 

 differ considerably from the type and belongs perhaps to Stoliczkaia. Pe- 

 trascheck accepts the determination of Geinitz but does not figure any 

 specimen which shows the transition between the smooth ventral part and 

 the form in which the ribs pass the venter without interruption. 



Kossmat 6 has noted the external similarity between Acanthoceras vici- 

 nale Stoliczka 7 and "Buchiceras" Swallovi Shumard, indicating at the same 

 time the difference in the suture which is much more complicated, especially 

 in the auxiliary saddles of the Indian species. 



Still more similar to M. Swallovi is a cephalopod from Madagascar de- 

 scribed by Boule, Lemoine and Thevenin 8 under the name of Acanthoceras 

 (Prionotropis) subvicinale. The suture of these specimens coincides per- 

 fectly with that of Metoecoceras, as has already been observed by the au- 

 thors, but it also has a great similarity with Pulchellia. The specimens are 

 very small and show an ornamentation very similar to that of Metoecoce- 



^tanton, Colorado Form., p. 168, pi. 38 (Buchiceras Swallovi White; according to 

 Hyatt, this is a new species, M. Whitei, Hyatt). 



2 Hyatt, Pseudocer. 



3 D'Orbigny, Pal. fran c.,terr. cret., ceph. p. 325, pi. 97, figs. 1-2 (under the name of 

 Am. catillus Sow.; this determination was corrected by d'Orbigny in Prodrfime II, 

 p. 146). 



4 Gueranger, Album Paleontol., pi. 5, fig. 2. 



5 Geinitz, Elbthalgebirge I, p. 280, pi. 62, fig. 3. 



6 Kossmat, Siidind. Kreideform., p. 201 (105). 



'Stoliczka, Ceph. Cret. Rocks India, p. 84, pi. 44. Kossmat, Siidind. Kreideform.. 

 p. 200 (104), pi. 25 (11), fig. 2. 



"Boule, Lemoine et Thevenin, Diego-Suarez, p. 31, pi. 8, fig. 5; fig. 16 of the text. 



