444 PROF, C, E. BEECHER ON PALHOZOIC  [Aug. 902, 
The abdominal segments are not well preserved, but appa- 
rently did not differ much in length, and were without conspicuous 
ornamentation. The telson and cercopods were evidently quite 
similar to the same structures in LH. socialis from the Chemung 
Group (Devonian). 
The type-specimen has a length of 25 millimetres, of which about 
6 mm. pertain to the postabdomen, 9 mm. to the abdomen, and 
10 millimetres to the cephalothorax. 
Distribution.—In the shales of the Waverly Group, Lower 
Carboniferous, near Warren (Pennsylvania). 
The denticulate border of the valves at once distinguishes this 
form from any other that belongs to the genus Hchinocaris. In this 
character, it is exceeded by the curious Pephricarts horripilata of 
Clarke,’ which also has a postabdomen of entirely different form, 
and is without the curved sigmoid carina so characteristic of 
Echinocaris. This species is dedicated to Dr. John M. Clarke, 
State Paleontologist of New York, who has contributed so much 
to a knowledge of the American fossil Phyllocarids. 
TROPIDOCARIS. 
Since the present material affords a number of structures hitherto 
lacking, and necessary for a consideration of the relations and 
affinities of Z'ropidocaris with other genera, it 1s now possible to 
define this genus quite fully. 
The valves of the carapace are obliquely truncate behind, 
marked by one or more longitudinal carine, separated by a median 
lanceolate plate along the thoracic region, and by an elongate rostral 
plate in the cephalicregion. Cephalic area not strongly marked, 
but generally indicated by indistinct rounded elevations, or by a 
difference in convexity from the remainder of the valve; ocular node 
usually at the end of a short carina, and with a minute pit at the 
summit. Abdomen with two exposed segments, cylindrical in 
form. Caudal plate short, with telson-spine shorter than the 
cercopods. 
Type, Tropidocaris bicarinata, Beecher. 
Hall & Clarke? first showed the existence of a rostral plate in 
Tropidocaris, and this, together with the recent discovery of the 
median lanceolate plate, necessitates the removal of the genus 
from the Echinocaride. The same structures are here shown in 
Elymocaris ; hence this, too, will have to be placed with Z'ropido- 
caris in another family. In Kastman-Zittel’s ‘ Text-Book of Palzon- 
tology ’ (1900) p. 657, Clarke established the suborder Rhinocarina 
for Phyllocarida possessed of these distinctive features. The single 
family of this suborder, the Rhinocaride (Clarke), was made to 
comprise the genera Rhinocaris, Clarke, and Mesothyra, Hall & 
1 *Notes on some Crustaceans from the Chemung Group of New York’ 
N.Y. State Mus. 49th Ann. Rep. 1895, vol. ii [1898] pp. 731-33. 
2 ‘Paleont. of N. Y.’ vol. vii (1888) p- 184. 
