THE 
GEOLOGICAL MAGAZINE. 
NEW ©SERIES 7 DECADE ‘Ill. VOEIIN. 
No. IV.—APRIL, 1888. 
Ore GIN PAS, Avestan ees Ss 
Lato 
T.—On Some ScanpDInaviAN Puoybiocaripa. 
By Prof. T. Ruperr Jonus, F.R.S., and Dr. Henry Woopwarp, F.R.S. 
(PLATE VI.) 
(Continued from page 100.) 
7. Tae Gastric Trera or Ceratiocaris. Pl. VI. Figs. 8, 9, 10; 
and Woodcuts, Figs. 1-9. 
N the Groroercan Magazine, Vol. II. 1865, p. 401, some account 
was given of the curious gastric teeth of Ceratiocaris and 
Dithyrocaris, from the Upper-Ludlow and Carboniferous strata of 
Scotland and Ireland; and in the Article Crustacna, by the same 
author, in the “ Encyclopedia Britannica,” vol. vi. 1877, p. 639, fig. 
13, the relationship of such internal masticatory organs to the 
stomach of the Crab and Lobster, in particular, was treated in detail. 
Bohemian specimens.—The late M. Barrande, in his ‘Syst. Silur. 
Bohéme,” vol. i. Supplm. 1872, p. 448, plates 18, 21, and 31, described 
and figured several gastric teeth, presumably of more than one species 
of Ceratiocaris, which he had obtained from his ‘Stage H-e 2,” 
equivalent to the lower divisions of Murchison’s ‘‘ Upper Silurian.” 
These little fossils were found in the same beds with Ceratiocarides,' 
but could not with certainty be referred to their species. He described 
them as having a general resemblance among themselves, being 
somewhat crescent-shaped, slightly concave on one side and convex 
on the other, with the middle part thicker than the ends. He does 
not appear to have met with any having a basal, root-like or fang- 
like portion attached. The number of cusps observed by M. Barrande 
nearly always amounted to six, the exceptions being perhaps due (he 
thought) to the age of individuals. 
In some of the forms from Bohemia each cusp (seen from above) 
has the shape of a chevron, more or less distinct according to its 
place in the series; the strongest being in the middle, and the weakest 
towards the ends. Each chevron is hollow and sloping, with sharp 
borders. Thus, seen from above, the surface has a sharp, flexuous or 
zigzag ridge ; each bend forming a chevron and cusp. When perfect, 
there is a sharp point at the top of the chevron of each cusp, and 
often a smaller tubercle at each of its lower ends. In his pl. 21, 
figs. 41, 42, and 43, the chevrons of this zigzag ridge usually open 
1 The species of Phyllocarida found in this Stage were Ceratiocaris Bohemica, C. 
docens, C. inequalis, with Aristozoé inclyta and A. Jonesi. 
DECADE III.—VOL. V.—NO. IV. 10 
