1868.] WOODWARD SILURIAN CRUSTACEA. 293 



Sixth segment 8 lines in length, by 3f in breadth ;^ surface punc- 

 tated. 



Seventh segment 11 lines in length, by 2-2. in breadth, punctated 

 as in the preceding. 



Eighth segment 1 inch in length and IJ inch in breadth, punc- 

 tated. 



Ninth segment 10 lines in length and IJ inch in breadth. 



Tenth segment 10 lines in length and 1^ inch in breadth. 



Eleventh segment 11 lines in length and 1^ inch in breadth. 



Twelfth segment 1 inch in length and 1 inch in breadth. 



Telson wanting, probably ensiform as in other species of Eu- 

 rypteriis. 



The punctate ornamentation (PI. IX. fig. 16) is well seen on the 

 anterior body-segments, and is at once readily to be distinguished from 

 the scale-like markings seen on the body of Pterygotus and Slimonia. 



3. EuRYPTERus OBEsus, sp. nov. PL X. fig. 1 . 



This little form is remarkable for the great obesity of the thoracic 

 somites, the breadth of the fourth segment being equal to the length 

 of the first eight segments. 



The carapace is 6 lines in breadth at its posterior border ; the 

 lateral and anterior borders form a semicircle; the length is 3 lines. 



The surface of the carapace and segments was extremely thin, as 

 shown by the puckered condition of the entire surface. The dorsal 

 surface, which is exposed to view, displays two eyes, placed 2| lines 

 apart, and two subcentral ocelli. Eive pairs of appendages are pre- 

 served in situ : — 



First, a pair of simple cylindrical antennae (7?-jointed), 4 lines 

 in length. 



Second, third, and fourth pairs alike, and about 9 lines in length ; 

 seventh joint unguiform. 



Fifth pair of maxillipedes 1 inch in length ; third, fourth, and 

 fifth joints small and somewhat narrow, sixth as broad as it is long; 

 seventh nearly oval, with small terminal talon, and united to the 

 sixth joint by a small intercalated triangular plate. 



Body -segments. — Xo ornamentation is visible on these, save a 

 quadrilinear series of markings extending to the seventh segment*. 

 First segment 6 lines in breadth and 1 line in length ; second seg- 

 ment 8 lines in breadth and 1 line in length ; third segment 9^ lines 

 in breadth and 1 line in length ; fourth segment 11 lines in breadth, 

 by 1| line in length ; fifth segment 11 lines in breadth, by 2 lines in 

 length ; sixth segment 11 lines in breadth, by If line in length ; 

 seventh segment 10 lines in breadth, by 1| line in length ; eighth 

 segment 7 lines in breadth, by 2 lines in length; the border of this 

 segment slopes rapidly inwards posteriorly, and is arched laterally ; 

 ninth segment 3 lines in breadth and 2 lines in length ; tenth seg- 

 ment 3 lines in breadth and 2 lines in length ; eleventh segment 

 2\ lines in breadth and 2| lines in length ; twelfth segment 2 lines 



* Bilinear markings are seen on the eighth and ninth segments. 



