28 bulletin: museum of comparative zoology. 



The Calymene abundant at Waldron, Indiana, has always been 

 identified with C. niagarensis, but differs from that species in at least 

 two marked details. The first and most obvious characteristic is that 

 there is no lip, nor any furrow between the glabella and the rim, so 

 that the glabella reaches upon, and in some cases, overhangs the rim, 

 a feature usual in the Cheiruridae but extremely uncommon among 

 the Calymenidae. This gives the cephalon the high, short appearance 

 which suggested the name breviceps. On the pygidium the ribs reach 

 nearly to the margin but become faint on approaching it. Ordinarily 

 the ribs do not bear any median impressed line though traces of one 

 may be seen on some specimens. 



This species is in many ways much like C. celebra, the next species 

 described. 



Formation and locality: — This species is so far known only from the 

 (Silurian) Waldron shale at Waldron, Indiana, where it is very com- 

 mon. 



Calymene celebra, sp. nov. 

 Plate 3, fig. 9, 10. 



Calymene hlumenhachii var. niagarensis Hall, Geol. surv. Wise, 1862, 1, p. 432. 



Calymene niagarensis Hall, 18th Rept. N. Y. state cab. nat. hist., 1865, p. 30, 

 adv. sheets; 20th Rept. N. Y. state cab. nat. hist., 1868, p. 334; 1870, 

 rev. ed., p. 425 Weller, Bull. Chicago acad. sci., no. 4, pt. 2, p. 261, pi. 

 23, f. 9-10. 



One of the most abundant of the trilobites of the Chicago area and 

 of southeastern Wisconsin is a Calymene which is constantly identified 

 as C. niagarensis. It is quite commonly found entire, but always so 

 far as I have seen in the condition of a cast of the interior. Moulds 

 of the exterior are common, but seldom complete. 



The cephalon is like that of C. niagarensis, with a short lip and 

 narrow furrow in front of the glabella. The dorsal furrows are always 

 very deep and sharp, but this is due to the state of preservation. The 

 glabella tapers rather abruptly toward the front. The basal lobes are 

 large, rounded, almost isolated; the second lobes small and rounded, 

 the intermediate "extra lobes" not very prominent. The third lobes 

 are very small and the fourth ones just barely indicated. The frontal 

 lobe is short and rather square at the front. The eyes are close to the 

 glabella and opposite the furrows between the second and third pairs 

 of lobes. 



