448 
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ase 
PROF. C. E. BEECHER ON PALZOZOIC [Aug. I9go02, 
widest just in front of the mid-length, and hasa single carina orna- 
mented with a chevron-pattern of oblique strie directed forward. 
The specimen illustrated in Pl. XIX, fig. 7, has the abdomen 
detached, and lying along the ventral border of the carapace. The 
distal somites are those which are normally exposed, the others in 
front being considerably shorter, with a progressively thinner test. 
Altogether, there are six somites preserved in front of the post- 
abdomen. The four anterior somites have a single, deep, lateral, 
longitudinal groove, which is not produced by compression as is a 
similar appearance shown on the two posterior segments. On the 
ventral side, there are thickenings and infoldings of the test, pro- 
bably for the attachment and support of muscles. 
The mandibles, or gastric teeth, are short, triangular, and 
without cusps, closely resembling those in Echinocaris socialis. 
The valves range in length from 8 to 33 millimetres. 
Distribution.—All the known specimens have been obtained 
from the Phyllocarid-Beds of the Chemung Group (Upper Devonian), 
at Warren (Pennsylvania). 
EXPLANATION OF PLATES XVII-XIX. 
[The specimens illustrated in these plates are in the collections of 
the Yale University Museum, New Haven, Conn. | 
Prats XVII. 
Echinocaris socialis, Beecher. 
A large and nearly entire individual : showing the form and ornamentation 
SIO Oe 
Fig. 8. 
of the carapace, the six abdominal somites, with the telson and right 
cercopod. Enlarged 2 diameters. Chemung Group, Upper Devonian. 
Warren (Pennsylvania). 
Puate XVIII. 
Echinocaris socialis, Beecher. 
. A specimen preserving the carapace and abdomen entire: showing the 
mandibles projecting in front. Enlarged 2 diameters. 
. Asimilar example, with the mandibles also exposed. Enlarged 2 dia- 
meters. 
. The postabdomen, with one abdominal somite : showing the form and 
length of the telson and cercopods. Enlarged 2 diameters. 
. The dorsal side of a single somite. Enlarged 4 diameters. 
. The ventral side of the same. 
. Anterior-end view of the same. 
The mandibles, as found on the underside of a carapace. Enlarged 
4 diameters. 
Chemung Group, Upper Devonian. Warren (Pennsylvania). 
Echinocaris Randal, sp. nov. 
The right valve: showing the form and disposition of the nodes and 
carina. Enlarged 2 diameters. 
Waverly Group, Lower Carboniferous. Warren (Pennsylvania). 
Echinocaris Clarkii, sp. nov. 
Fig. 9. The type-specimen: showing the general form and proportions. 
Enlarged a little more than 2 diameters. 
Waverly Group, Lower Carboniferous. Warren (Pennsylvania). 
