INVERTEBRATES. 395 



caudal segment mentioned by Pictet, none of our specimens being in a condi- 

 tion, to show the connection of that appendage with the abdomen satisfactorily, 

 while he does not explain in what the difference consists. 



Bellinurus Dan^e, M. and W. 



PL 32, fig. 2, 2 a. 



Bellinurus Danx, Meek and Worthen, March, 1865. Proceedings Acad. Nat. Sci., 

 Philad., p. 43. 



Cephalo-thoracic shield transversely crescentric, more than 

 twice as wide as long, moderately convex, the height nearly 

 equaling half its length ; anterior and antero-laterai margins 

 broadly and regularly rounded; lateral angles produced obliquely 

 backwards and outwards, with a very slight inward curve, 

 into slender mucronate spines, terminating remote from, and 

 nearly opposite the middle of the abdomen ; posterior margin 

 on each side for about two-thirds of the way in from the lateral 

 angles, toward the middle, concave in outline ; nearly straight 

 or very slightly concave along the middle between these points. 

 Mesial lobe small, somewhat lower than the ocular ridge on 

 either side, but rounde'd and well defined behind, where it 

 supports a small central tubercle (or short spine ?) , thence nar- 

 rowing forward, and sometimes showing a slight tendency to 

 develop a second much smaller tubercle, at about one-third 

 the length of the shield from its posterior margin — near 

 which point it suddenly contracts into a mere linear carina, 

 that extends forward to the anterior transverse division of the 

 ocular ridge. Area included by the ocular ridge, crown- 

 shaped or subquadrangular in outline, and composing the cen- 

 tral third of the cephalo-thoracic shield ; a little wider anteri- 

 orly than its length, which equals about five-sixths that of the 

 shield; lateral margins concave in outline; anterior side con- 

 vex, with a central emargination; internal surface divided into 

 four irregular subordinate areas, by the mesial lobe with its 



