OP ARTS AND SCIENCES. 17 



late, its posterior portion and the post-thoracic plate more distinctly, 

 while the abdomen is profusely and rather sparingly punctate. Length 

 20 mm. Greatest breadth 10 mm. Mazon Creek, 111. (Coll. R. D. 

 Lacoe, No. 1701.) A fuller description and figure will be given at 

 another time. 



The specimen is interesting as preserving very completely the left 

 palpus. 



Architarbus Scudder. 



Cephalothorax orbicular, broadly rounded in front, much smaller 

 than the abdomen, but not separated from it by a marked lateral con- 

 striction. Coxo3 radiating from a central pit. Abdomen oval, com- 

 posed of nine segments, of which those on the basal half are very 

 much shorter than the others, and on the dorsal surface are forced 

 still more closely together by the larg-e post-thoracic plate. 



Architarbus rotundatus Scudder, Worth, (ieol. 111., iii. 568, fig. 4^ 

 1868. Mazon Creek, 111. 



Architarbus subovalis Woodward, Geol. Mag., ix. 385-387, pi. 

 9, fig. 1% l"*, 1872. Lancashire, England. Here probably belongs 

 Curculioides Ansticii Buckl. Geol., ii. 76, pi. 46", fig. 1, 1837. 

 Coalbrookdale, England. 



Architarbus silesiacus Roemer, Jahresb. schles. Gesellscb. vaterl. 

 Cult., Ivi. 54, 55, 1879. Glatz, Silesia. 



Anthracomartds Karsch. 



Cephalothorax quadrate, the front square or scarcely convex, about 

 half the size of the abdomen ; coxa3 radiating from a broad triangular 

 sternal plate, the base of which forms the posterior margin. Sides of 

 the body constricted so as to show a distinct though generally slight 

 separation of cephalothorax and abdomen. Abdomen orbicular, com- 

 posed of seven segments of similar length throughout. 



Anthracomarfus Volkelianus Karsch, Zeitschr. deutsch. geol. Ge- 

 sellsch., 1882, pp. 556-561, pi. 21, figs. 1, 2. Neurode, Silesia. 



Anthracomarfus Krejcii Kusta. Sitzungsb. bcihm. Gesellsch. Wiss.? 

 October 12, 1883, pi., figs. 1-3, 1883. Rakonitz, Bohemia. 



Anthracomartus tri/obiius nov. sp. Sides of the cephalothorax an- 

 gulated in the middle of the posterior half, behind which it narrows 

 rapidly, showing a very marked constriction between it and the abdo- 

 men. The latter of equal length and width, broadest behind the 

 middle, and furnished with a marginal flange nearly as broad as the 

 lateral fields. Whole body delicately and uniformly punctate. 

 Length 17.5 mm.; greatest width 11.25 mm. Fayetteville, Ark. 



VOL. XX. (n. S. XII.) 2 



