PERISPHINCTES SUBBAKERLE. 49 



and was obtained from the higher part of the Cornbrash, i. e. above the Avicula 

 echinata nibble at East Fleet, near Weymouth. It is at present unique. 



This species agrees exactly in the numerical characters with the side view of 

 the shell figured by Quenstcdt (Am. Schwabische Jura, pi. lxxix, fig. 3) as one 

 variety of Am. sublaevis, to which, however, he assigns no special name. It agrees 

 also in the description of the ornaments and length of the body chamber. With 

 regard to its thickness, this is only given by the statement that the back is arched 

 like a half-moon, which with the figure indicates an agreement with our species. 

 Very probably the two forms are the same, both being companions of the Maero- 

 cephalites, but as, in any case, a new name is required, one source of error is 

 eliminated by assuming the present as the type. As it rather varies from the 

 generic definition of "very inflated," it would be better that, in this case, the 

 latter were altered to "more or less inflated." It is probably an introductory 

 species to the fully characterised genus. 



Distribution. — In the upper part of the Cornbrash, only at East Fleet. 



Gmus PERISPHINCTES, Waagen. 



1869. Beneeke, Beitrage, vol. ii, pt. ii. 



The genus, as defined by its author, is intended to include all the Planulata 

 of the Middle and Upper Jura. In youth, and nearly to age, the aperture shows 

 auricles, and the earlier whorls at least show constrictions. Body chamber f-1 

 whorl. Thus widely defined it has since been separated by Siemiradzki ( Palaeon- 

 tographica, vol. xlv, 1898-99) into six divisions, to which, in some cases, generic 

 or subgeneric names have been applied. In the case of the Cornbrash fossils, at 

 least, I see no advantage in adopting these minuter groups; only 11 species 

 out of 367 are recorded as comino; from horizons earlier than the Callovian. 



Perisphinctes subbakeriae (D'Orbigny). Plate V, fig. 2. 



1843. Ammonites triplicatus, Quenstedt (non Sowerby), Floetzgebirge Wiirttembergs, p. 364. 



1845. bakerix, D'Orbigny (non Sowerby), Pal. Franc. Terr. Jurass., pi. cxlviii (non pi. cxlix). 



1849. — triplicatus, Quenstedt (non Sowerby), Petref Deutsch. Cephalopoden, pi. xiii, fig. 7> 



p. 171. 



1850. — subbdkerise, D'Orbigny, Prodrome, et. 11, No. 11. 

 1858. — triplicatus, Quenstedt, Jura, pi. lxiv, figs. 17-19. 

 1858. — funatus, Oppel, Juraformation, p. 550. 



1883. — triplicatus, Quenstedt, Arniu. Schwiibischen Jura, p. 680, pi. lxxxvi, fig. 2. 



7 



