91 



versing the joints, without grooves; articulations of 

 the side lobes being manifest continuations of those of 

 the middle lobe, and consequently, agreeing in num- 

 ber. 



BRONGNIATIA PLATYCEPHALA. Eaton. 



Head and fore abdomen very broad and depressed, 

 the abdomen with ten joints curved forwards at the 

 undulations; post abdomen and tail with about fif- 

 teen joints curved backwards at the undulations; the 

 three lobes of the tail more distinctly separated; divi- 

 sions between the joints of the abdomen double. 



The representation of B. platicephala, figure 20, 

 plate 2, of the Geological Text Book, if it be accu- 

 rately drawn, is certainly of a trilobite never before 

 described. On the buckler, which is without eyes, 

 there is delineated a figure, not unlike some of the 

 leaves of the mulberry tree. 



The tail is also very peculiar. In Silliman's Jour- 

 nal, Volume 21st, page 136, Professor Eaton pro- 

 posed for this curious fossil the temporary name of 

 Ogygies latissimus. "It is found, he observes, in the 

 upper soft slaty variety of the rock which has been 

 so successfully used for the lias cement at Chitteningo, 

 Sec. Dr Smith, of Lockport, (N. Y.) sent me two 

 specimens, taken from a continuation of the Chitten- 

 ingo lias rock, immediately beneath the geodiferous 

 lime rock on which the cherty (cornitiferous) re- 

 poses." The whole animal is six inches long, and 

 three broad. 



